A TREATISE 
 
 DIAMONDS AND PEARLS 
 
A 
 
 TREATISE 
 
 DIAMONDS AND PEARLS; 
 
 IN WHICH 
 
 THEIE IMPOBTANCE IS CONSIDEKED ; 
 
 PLAIN RULES ARE EXHIBITED FOR ASCERTAINING THE 
 VALUE OF BOTH; 
 
 THE TRUE METHOD OF MANUFACTURING 
 DIAMONDS. 
 
 DAVID JEFFRIES, 
 
 JEWELLER. 
 
 JFourtfj lEfoitum, foittj large Emprofoemmts. 
 
 LONDON: 
 
 TO BE HAD OF E. LUMLEY, 56, CHANCERY LANE. 
 (Price to Subscribers, II. Is.) 
 
LONDON : 
 
 PRINTED BY STEVENS AND CO., BKLL YARD, 
 TEMPLE BAR. 
 
TO THE READER. 
 
 As the following treatise is calculated to 
 inform the world concerning the value of 
 diamonds and pearls ; the weights made use 
 of relative thereto are here previously ex- 
 plained, as the knowledge of them will be 
 found necessary to the public. They agree the 
 nearest to troy weight of any other, and are 
 commonly called carat weights ; 150 carats 
 make about an ounce of that weight. Carats 
 are divided into halves, quarters, or grains; 
 eighths, sixteenths, and thirty-two parts. 
 
 The draughts of the sizes of brilliant and 
 rose diamonds, exhibited in the plates, are 
 tests to prove the truth and defects of the 
 manufacture of any diamond, and will be 
 found as necessary as scales and weights, in 
 attaining to a right judgment of their value. 
 To make the truth of this assertion appear 
 more evident, it is here to be observed ; 
 first, that either a brilliant or rose diamond 
 may be wrought in such a manner as to con- 
 
 34B8B.3 
 
vlii TO THE READER. 
 
 tain one fourth, or even one third, more 
 weight than it ought to have, which neces- 
 sarily injures the beauty of its form, and 
 likewise injures its true spirit and lustre ; 
 and, if that overweight be injudiciously va- 
 lued, together with its due weight, the price 
 will be thereby greatly heightened above its 
 just value, more especially in large diamonds. 
 All which overweighted stones will easily be 
 discovered by the sizes exhibited in the 
 plates, which exactly shew the true expan- 
 sion of well-wrought diamonds. 
 
 Secondly, it is to be observed, that the 
 sizes before referred to will discover if any 
 stones do not carry their true substance. An 
 important circumstance to be regarded, inas- 
 much as any degree of want thereof neces- 
 sarily lessens the spirit and lustre they would 
 otherwise be possessed of. In both cases, 
 directions are given in the treatise, in what 
 manner every such stone is to be valued, as 
 well as all other well-proportioned ones, ac- 
 cording to their water, and several degrees 
 of perfection or imperfection, of what size or 
 weight soever. 
 
TO THE QUEEN. 
 
 MADAM, 
 
 I BEG leave, with the profoundest hu- 
 mility, to dedicate the following Trea- 
 tise to your Majesty, the patron of 
 truth and justice, and friend to the 
 common interest of mankind, more 
 particularly to that of your Majesty's 
 subjects : in which your royal character 
 shines with the brightest lustre. 
 
 It contains rational and plain rules 
 for estimating the value of diamonds 
 and pearls under all circumstances, and 
 for manufacturing diamonds to the 
 greatest perfection : both which have 
 hitherto been but very imperfectly un- 
 derstood. From hence, all property of 
 this kind has been exposed to the great- 
 est injury, by being subject to a capri- 
 cious and indeterminate valuation ; and 
 
 A2 ' 
 
VI DEDICATION. 
 
 the superlative beauty of diamonds has 
 been much debased. 
 
 To countenance a work calculated 
 to promote a general benefit, it is hum- 
 bly apprehended, will not be deemed un- 
 worthy the condescension of a crowned 
 head, as these jewels constitute so large 
 a part of public wealth ; and as they 
 are, and have been in past ages, the 
 chief ornaments of great and distin- 
 guished personages, in most parts of 
 the world. 
 
 That the supreme Disposer of all 
 things may long preserve your Majes- 
 ty, the guardian of the commerce and 
 properties of these your kingdoms, and 
 that you may continue to reign in the 
 hearts of a grateful and loyal people, is 
 the fervent prayer of, 
 
 May it please your Majesty, 
 
 Your Majesty's most dutiful and 
 most faithful subject, 
 
 DAVID JEFFRIES. 
 
POSTSCRIPT. 
 
 THE price of this book, I hope, will not be 
 thought too large, when the following matters 
 are taken into consideration. 
 
 First, that of its being calculated to settle 
 the value of diamonds and pearls, on a ra- 
 tional and firm basis ; a circumstance of no 
 small concern, inasmuch as their worth has 
 hitherto been rated by fancy and caprice, 
 which has frequently proved very injurious 
 even to traders in them, as well as to others 
 who have bought them for their use. 
 
 Next, as the subject concerns only per- 
 sons of rank and fortune, and those of the 
 trade for whose use the book is principally 
 designed, the sale of it is not like to be very 
 large. To this may be added, that what it 
 
X POSTSCRIPT. 
 
 contains is the product of many years' study, 
 and difficult labour of various kinds, attend- 
 ed with an expence much beyond what can 
 readily be imagined. 
 
 And here T shall take leave to observe, 
 that inasmuch as the tables of the prices of 
 diamonds and pearls answer the same pur- 
 poses in attaining to the knowledge of the 
 value of these jewels, as scales and weights, 
 they may be considered in the same light ; 
 and, that the diamond sizes may be depended 
 on for their truth, they are all engraved by 
 myself, not daring to trust that performance 
 to any one else ; which is likewise the case 
 in respect to some other things, that I shall 
 not here particularize : all which have in- 
 grossed my thoughts and time to the neglect 
 of my private concerns : by that means I 
 have greatly injured a fortune (not got by 
 trade) that put me above entering on this 
 work with any mean lucrative views ; and 
 least of all that of publishing for the sake of 
 the profit that might arise therefrom. On 
 
POSTSCRIPT. XI 
 
 the contrary, my former circumstances ena- 
 bled, and my inclinations led me to engage 
 in this attempt, in order to serve the public, 
 and the jewel trade. And to my great sa- 
 tisfaction, I find the principles of the book 
 begin already to operate ; from whence it 
 may be presumed they will more and more, 
 and that the world will experience their uti- 
 lity. That this was my original motive is a 
 fact well known to some ; and that I former- 
 ly intended to have published the matters 
 contained in this treatise, without having 
 any regard to the profit arising thereby. 
 These circumstances, doubtless, will have 
 their due weight in accounting for the price 
 of the book. 
 
 And now I think it my duty to mention, that 
 whatever knowledge I may have acquired 
 by applying my thoughts and time this way, 
 I shall endeavour faithfully to employ in any 
 business that I may be honoured with in 
 the jewelling trade. This I have not spoke 
 of in my former edition, nor should I now, if 
 
Xll POSTSCRIPT 
 
 I were not countenanced in so doing by some 
 persons of rank, and many of my particular 
 friends, both which have of late favoured me 
 that way : and this leads me to hope for an 
 increase thereof, which I flatter myself will 
 not be found disadvantageous to any that 
 may engage me in their service. In saying 
 this I am not apprehensive of having said 
 too much. 
 
AN EXPLANATION 
 
 OF SOME TECHNICAL TERMS MADE USE OF Iff THIS 
 TREATISE, IN ALPHABETICAL ORDER. 
 
 THE bezils are the upper sides and corners 
 of the brilliant, lying between the edge of 
 the table and the girdle. 
 
 The collet is the small horizontal plane, or 
 face, at the bottom of the brilliant. 
 
 The crown is the upper work of the rose, 
 which all centres in the point at the top, and 
 is bounded by the horizontal ribs. 
 
 The facets are small triangular faces, or 
 planes, both in brilliants and roses. In bril- 
 liants there are two sorts, skew or skill-fa- 
 cets, and star-facets. Skill-facets are divided 
 into upper and under. Upper skill-facets 
 are wrought on the lower part of the bezil, 
 and terminate in the girdle ; under skill fa- 
 cets are wrought on the pavilions, and ter- 
 minate in the girdle ; star-facets are wrought 
 
XIV 
 
 on the upper part of the bezil, and termi- 
 nate in the table. 
 
 The girdle is the line which encompasses 
 the stones, parallel to the horizon ; or, which 
 determines the greatest horizontal expansion 
 of the stones. 
 
 Lozenges are common to brilliants and 
 roses. In brilliants they are formed by the 
 meeting of the skill and star facets on the 
 bezil : in roses, by the meeting of the facets 
 in the horizontal ribs of the crown. 
 
 Pavilions are the under-sides and corners 
 of the brilliants, and lie between the girdle 
 and the collet. 
 
 The ribs are the lines, or ridges, which 
 distinguish the several parts of the work, 
 both of brilliants and roses. 
 
 The table is the large horizontal plane, or 
 face, at the top of the brilliant. 
 
CONTENTS. 
 
 PAGE 
 
 INTRODUCTION . . . . .1 
 
 Of the production of Diamonds and the principle of valuing 
 them ..... 5 
 
 Of Brilliant Diamonds, and the method of manufacturing them 9 
 Of the sizes or expansion of Brilliants . 16 
 
 Of the use of the Brilliant sizes in discovering ill-wrought 
 ones ..... 18 
 
 Of the method of manufacturing, and valuing, Spread Bril- 
 liants . . . . . .21 
 
 Of Rose Diamonds . . . .24 
 
 Of the impropriety of transforming well-wrought Rose Dia- 
 monds into Brilliants . . . .26 
 
 Of the form of a Rose Diamond . . .27 
 
 Of the manufacture of a Rose Diamond . . 29 
 
 Of the sizes of Rose Diamonds, and their use in discovering 
 ill-made ones . . . .31 
 
 Of the method of manufacturing and valuing Spread Rose 
 
 Diamonds . . , . .32 
 
 Of the first method of valuing wrought Diamonds, in con- 
 junction with Rough Diamonds, out of which they are 
 supposed to be wrought . . .34 
 
 Of the second method of valuing wrought Diamonds, in 
 conjunction with the Rough Diamonds, out of which they 
 are supposed to be wrought . . .41 
 
 Of the method of valuing wrought Diamonds, exclusive of 
 any regard to Rough Diamonds . . 4,4 
 
XVI CONTENTS. 
 
 PAGE 
 
 Of the highest and lowest prices of Rough and Polished 
 
 Diamonds . . . . .48 
 
 Remarks on Brazil Diamonds . . . 51 
 
 Of the table of prices of Diamonds . . .67 
 
 Of the innate perfections, imperfections, and Water of 
 
 Diamonds . . . . .72 
 
 Of the superior Worth of Diamonds over all other jewels . 74 
 Reasons for working Diamonds in a complete manner, and 
 
 the consequences resulting from a contrary practice . 76 
 
 Of the use of the sizes in purchasing Rough Diamonds . 85 
 Remarks on the India manufacture of Diamonds, and their 
 
 custom in regard to Rough Diamonds . . 87 
 
 Some account of authors, who have heretofore treated of 
 
 Diamonds and Pearls, and the improvements which have 
 
 been made since their times . . .92 
 
 Of Pearls, their perfection and imperfection . . 96 
 
 Of the rule of valuing Pearls . . .97 
 
 Observations on the losses supposed to be sustained by the 
 
 purchase of Jewels .... 107 
 
 Conclusion . . . . '": . 113 
 
INTRODUCTION. 
 
 DIAMONDS and pearls being, of all jewels, 
 of the greatest importance to this and 
 most nations of the world, justly demand 
 the highest regard of any ; inasmuch as 
 they constitute the largest share of wealth 
 of this kind, and are the chief ornaments of 
 great and distinguished personages : more 
 especially diamonds, as being the most 
 beautiful and valuable of all. On which 
 account, as I have been above thirty 
 years a considerable trader in them, and 
 a manufacturer of diamonds, I have stu- 
 diously employed great part of my time in 
 search of rules to ascertain the value of 
 
2 INTRODUCTION. 
 
 both under all circumstances, whatever be 
 their weight and magnitude; and, likewise, 
 for manufacturing diamonds to the greatest 
 perfection. And apprehending that I have 
 fully succeeded for the promotion of the 
 commerce, and for the benefit of the pub- 
 lic, I have exhibited, in this treatise, means 
 by which the inquisitive may attain to a 
 right knowledge in these matters ; and 
 more especially concerning those from one 
 carat weight, to those of one hundred 
 carats. 
 
 The plates of the sizes of diamonds, and 
 the tables of the prices of both, are ex- 
 tended no farther than to diamonds and 
 pearls of that weight. They might be 
 carried on ad infinitum ; and the rule of 
 valuing will hold good, though they should 
 weigh as much as Governor Pitt's diamond, 
 purchased by the Regent Duke of Orleans 
 
INTRODUCTION. 3 
 
 for Louis the Fifteenth, then a minor, which 
 weighs 136 carats f ; or as three others 
 mentioned by Monsieur Tavernier, in the 
 second part of his voyages, p. 148, English 
 translation, viz. that of the Great Duke of 
 Tuscany, which weighs 139 carats \\ or 
 that in a merchant's hand, which weighs 
 242 carats TV ; or that of the Great Mogul, 
 which weighs 279 carats ?. 
 
 If what is contained in this treatise be 
 found true, it will confute the notion that 
 some diamonds and pearls are inestimable, 
 on account of their extraordinary magni- 
 tude ; which, to this time, prevails, upon 
 the supposition that no methods can be 
 found to determine their value ; and will 
 likewise greatly contribute to support the 
 dignity of the diamond manufacture. 
 

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TREATISE 
 
 ON 
 
 DIAMONDS AND PEARLS. 
 
 Of the Production of Diamonds and the Prin- 
 ciple of valuing them. 
 
 THAT rules may be given for the just 
 valuing of diamonds, according to their 
 increase in size and weight, is reason- 
 able to suppose, from this consideration ; 
 that nature has produced in times past, as 
 well as it does at present, diamonds in the 
 following manner, viz. a vast number of 
 small ones, and progressively a less number 
 of larger; and that they promiscuously in- 
 herit the same properties, and share alike 
 of perfection, and imperfection. This, there- 
 fore, is a sufficient foundation for rules to be 
 
6 A TREATISE ON 
 
 given for valuing them in proportion to their 
 size and weight, which will be found here- 
 after exhibited ; and if the use and appli- 
 cation of them were conformable to the 
 production of nature, the rules thus found- 
 ed and prescribed, would never be inter- 
 rupted : and, therefore, if the humour of the 
 world demands, at any time, more or less of 
 any particular sizes and weights than nature 
 provides, the price obtruded thereby must 
 be reckoned the occasional, and not the just 
 price, and complied with as such ; which 
 happens to be the case at present, by the 
 extraordinary use of small diamonds in the 
 decorations now fashionable in jewelling. 
 And as the price of these small diamonds 
 will always fluctuate by the alterations of 
 fashions, little regard will be had in this 
 treatise to any, under the weight of one 
 carat. 
 
 It may be also observed, that the value of 
 rough diamonds, from two to three carats, 
 and also of polished diamonds, from one to 
 one and a half, does not correspond with the 
 rules hereafter laid down ; the price at pre- 
 sent being lower than what is asserted by 
 
DIAMONDS AND PEARLS. 7 
 
 the rules ; which is acknowledged, and will 
 remain so, as long as the humour prevails 
 of supplying the place of diamonds of that 
 weight, by meanly setting small stones in a 
 cluster in their room, for the sake of a showy 
 and flashy appearance, at a less price than 
 stones of these sizes would admit of; by 
 which means these sizes are less used than 
 formerly, and become cheaper (the produc- 
 tion of nature being always the same), and 
 from hence they are depreciated in their va- 
 lue ; so that the present prices of these sizes 
 must also be reckoned the occasional, and 
 not the just price. 
 
 The rules are, nevertheless, just, uniform, 
 and consonant to nature ; and therefore are 
 here proper to be offered, in order to assist 
 in coming at the true knowledge of the 
 value of diamonds of a higher worth, than 
 such as are liable to be affected in their 
 price by the alteration of fashions in jewel- 
 ling. 
 
 The principle or rule is, that the pro- 
 portional increase, or value of diamonds, is, 
 as the square of their weight, whether rough 
 or manufactured. For the explanation 
 
8 A TREATISE ON 
 
 whereof, an instance is first given in rough 
 diamonds ; on which account it will be ne- 
 cessary to lay down a general price, which 
 is supposed to be 2 per carat; meaning, 
 the whole species, good and bad blended to- 
 gether, which are worthy the expence of 
 manufactory. For example, suppose the 
 value of a rough diamond of two carats, at 
 the rate of 2 per carat, should be required ; 
 the rule is, first, to multiply 2 by 2, which 
 makes 4, the square of its weight ; then 
 multiply the product of 4 by 2, the price 
 of one carat, that makes 8, which is the 
 true value of a rough diamond of 2 carats. 
 
 To make this rule applicable to manu- 
 factured diamonds, it will be necessary to 
 ascertain what waste, or loss of weight, will 
 be sustained in manufacturing them. And 
 here it may be advanced as a matter of fact, 
 that half the weight will be lost ; conse- 
 quently, doubling the weight of any manu- 
 factured diamond, renders the rule of the 
 same use to show their value. This loss is 
 to be understood to relate to the general 
 manufactory of brilliant and rose diamonds, 
 in the most perfect manner. To that end, 
 
DIAMONDS AND PEARLS. 
 
 rules are to be offered for a general practice 
 in both kinds of manufactory ; which, if 
 conformed to, will be found to exhibit dia- 
 monds in such a manner, as to be produc- 
 tive of greater perfection and saving of 
 weight, than any other standards of prac- 
 tice. 
 
 Of Brilliant Diamonds, and the Method of 
 manufacturing them. 
 
 BRILLIANTS are first to be considered. 
 And the manufactory of a square one is 
 fixed on for the fundamental and govern- 
 ing rule of practice ; nature for the most 
 part directing thereto, as it produces 
 abundantly more apparent six-pointed stones 
 than stones of any other form ; and be- 
 cause the same depth or substance, and 
 the same manner of proportioning that sub- 
 stance, which are essential in rendering a 
 square brilliant of any other shape complete ; 
 and more substance, or any other manner 
 of proportioning, will be found, upon ex- 
 perience, prejudicial to the beauty of their 
 B 2 
 
10 A TREATISE ON 
 
 form, and the true dignity of their spirit and 
 lustre, compared with such as are made 
 conformable to the following rules : 
 
 The form of a six-pointed rough diamond 
 is previously to be described ; as the shape 
 of it is not much known. 
 
 It is a figure composed of two square 
 pyramids, joined at their bases, and which 
 form an outline of a true square. The 
 whole figure is composed of eight triangular 
 faces or planes ; four above the base, and 
 four below it ; all meeting in two points, 
 one at top, the other at bottom ; terminat- 
 ing in the poles of the axis, or line passing 
 through the centre of the stone from top to 
 bottom. Some stones are found to answer 
 this figure very nearly. To make a com- 
 plete square brilliant from such a stone, if 
 it be not exactly true by nature it must be 
 made so by art. 
 
 The first thing therefore to be done, is 
 to reduce that part, representing the base 
 of the two pyramids, to an exact square, 
 which forms what is called the girdle of the 
 stone ; and then work by the square from 
 the girdle, which will produce the two 
 
DIAMONDS AND PEARLS. 11 
 
 points of the axis ; and, if it be truly exe- 
 cuted, the length of the axis from point to 
 point will be equal to the breadth of the 
 square from side to side. A draught of a 
 side-view of such a stone will be found in 
 the first plate, No. 1. 
 
 The next thing to be done, is to produce 
 the table and collet. In order to which, 
 divide the block into eighteen parts from 
 top to bottom ; and then take away from 
 the upper part &, and from the lower part 
 TV. This gives the upper part, or table 
 side, yV above the girdle, which is i of the 
 remaining substance ; and the lower, or col- 
 let side, T 8 8 or f ; only 12 of the original 
 18 parts being left in depth. And thus 
 the table and collet are formed, which will 
 be found to bear this proportion to each 
 other, viz. the collet will be one-fifth of the 
 breadth of the table. In this state it is a 
 complete square table diamond. 
 
 Its different parts are denoted by the let- 
 ters a, b, c, d, e. a, shows what is usually 
 called the table of the stone, which is an 
 horizontal 'plane at the top ; b, the upper 
 sides or bisils ; <?, the girdle, which shows 
 
12 A TREATISE ON 
 
 its expansion ; d, the undersides or pavi- 
 lions ; e, the collet, which is a small hori- 
 zontal plane at the bottom. The pricked 
 lines above the table, and those below the 
 collet, show what has been taken away. A 
 side-view of one will be found in Plate I. 
 No. 2. 
 
 Note. This species of manufactory has 
 been exhibited time out of mind ; and the 
 brilliant, which is an improvement upon it, 
 has been introduced within the last century; 
 as will appear to those who shall give them- 
 selves the trouble of an inquiry. But this 
 not being essential to the present undertak- 
 ing (which will be pursued with the utmost 
 brevity) an historical account of these mat- 
 ters is omitted. 
 
 This is the foundation of a square bril- 
 liant; and, in order to render it a perfect 
 brilliant, each corner must be shortened ^th 
 part of its diagonal ; and then the corner 
 ribs of the upper sides must be flattened, 
 or run towards the centre of the table i 
 less than the sides ; and the lower part, 
 which terminates in the girdle, must be I 
 of one side of the girdle ; and each corner 
 
DIAMONDS AND PEARLS. 13 
 
 rib of the under sides must be flattened 
 at the top, to answer the above flattening 
 at the girdle ; and at the bottom i of each 
 side of the collet. A side-view of one will 
 be found in Plate I. No. 3. 
 
 The parts of the small work which com- 
 pletes it a brilliant, are called star and skill 
 fassets, and are of a triangular shape. Those 
 which join to the tables are the star fassets, 
 those which join to the girdle the skill fassets. 
 Both of these partake equally of the depth 
 of the upper sides from the table to the 
 girdle, and meet in the middle of each side 
 of the table and girdle, as also at the cor- 
 ners ; and thus they produce regular lo- 
 zenges on the four upper sides and corners 
 of the stone. The triangular fassets on the 
 under sides joining to the girdle, must be 
 half as deep again as the above fassets, to 
 answer to the collet part : that is to say, in 
 the proportion of three to two. A draught 
 of a brilliant rendered complete, will be 
 found in Plate I. No. 4. 
 
 Under the before-mentioned draughts, are 
 represented four complete brilliants in a 
 horizontal view, by double draughts, weigh- 
 
14 A TREATISE ON 
 
 ing 36 carats each. No. 5 is a square ; No. 
 6, a round; No. 7, an oval; No. 8, a drop. 
 The left-hand draughts regard their upper 
 parts, and those on the right their under 
 parts, which are supposed to be divided at 
 their girdles. They are thus separately re- 
 presented, the better to show their whole 
 work, and in what manner it should lie ; and 
 likewise their size and expansion, and the size 
 of their tables and collets. 
 
 Note. Their perpendicular depths, from 
 table to collet, are shown by the length of 
 the bars placed under each double draught. 
 The octagon in the middle of the left-hand 
 draught of No. 5 is the table, which is an 
 horizontal plane or face, at the top, and is 
 denoted by the letter a. The triangular 
 fassets adjoining to the table are star fassets, 
 and are denoted by the letter b. Those ad- 
 joining to the extreme part or outlines, are 
 skill fassets, and are -noted by the letter c. 
 These, meeting in the middle of the upper 
 sides and corners of the stone, form figures 
 of a lozenge shape, round the upper sides 
 and corners of the stone, and are denoted by 
 the letter d. The outlines of this, and that 
 

 DIAMONDS AND PEARLS. 15 
 
 of the right-hand draught, are the girdle of 
 the stone, and are denoted by the letter e. 
 The triangular fassets adjoining to the out- 
 lines of the right-hand draughts, are the un- 
 der skill fassets, and are denoted by the letter 
 f. The lower sides are denoted by the let- 
 ter g. The octagon in the middle is the col- 
 let, which is denoted by the letter h ; and 
 is an horizontal plane or face, at the bottom 
 of the stone. This description serves as 
 an explanation of the other three double 
 draughts. All lines within the outlines of 
 the draughts, are called ribs in diamonds. 
 These draughts, with these explanations, will 
 always be found of use to give a right idea of 
 a brilliant diamond. In Plate VI. there is a 
 draught of an instrument, useful for examin- 
 ing the size and depth of any diamond, 
 called a prover. 
 
16 A TREATISE ON 
 
 Of the Sizes or Expansion of Brilliants. 
 
 IN Plates II. III. IV. V. is exhibited a list 
 of the draughts of the horizontal repre- 
 sentation of 55 square brilliants, from one 
 carat weight, to an hundred carats, ranged 
 in a progressive order, according to their 
 increase in size and weight ; which are so 
 many tests to prove the truth or error, of 
 the manufacture of any brilliant diamond. 
 Here it is to be observed, that their depths 
 are expressed by the length of the bars placed 
 under each draught ; and the size of their 
 
 O ' 
 
 collets, by the octagons under the bars, in 
 order more distinctly to discern their several 
 parts. The numerical figures on the left- 
 hand of each draught, regard their number; 
 those on the right-hand, their weight. 
 
 The reason why the number of size is not 
 more multiplied, is, lest the progression of 
 increase in size should not be discernible ; 
 and, by that means, should create too great 
 difficulty in adjusting the degrees in which 
 any stone departs from truth. And this the 
 rather, on account of other stones differing 
 
DIAMONDS AND PEARLS. 17 
 
 in their shapes at the table, girdle, and col- 
 let, from those of square brilliants ; which 
 increases, in some measure, the difficulty of 
 determining any difference to a great nice- 
 ty ; the use of the sizes being to expose any 
 considerable or gross departure from truth, 
 and to prevent the carrying on the base and 
 heavy manufacture, which has of late pre- 
 vailed in an extravagant degree, to the great 
 disparagement of the diamond species ; and 
 has contributed, likewise, to a great decep- 
 tion and imposition on the public. It may 
 with truth be said, regarding small stones 
 (which mean stones under the weight of a 
 carat), that, in general, they are so ill-made, 
 as to be void of their true beauty in all re- 
 spects ; and, by reason of their closeness or 
 want of due expansion, they will not fill up, 
 by one-fourth, the same space as well-made 
 stones do in a piece of jewelling work. Con- 
 sequently, they are so much less in appear- 
 ance ; and as they retain one-fourth more 
 weight than well-made stones of the same 
 expansion ; and, as they are wrought for one- 
 third, or half the price, the vendor of such 
 can afford to sell them at least 30 per cent, 
 c 
 
18 A TREATISE ON 
 
 less, than he can afford to sell well-made 
 stones. 
 
 The truth of these matters will evidently 
 appear by future inquiry and observation. 
 
 Of the Use of the Brilliant Sizes in discover- 
 ing ill-wrovght ones. 
 
 HERE it may be proper to show, how far 
 this ill manner of working before mentioned 
 may debase diamonds of larger sizes, and 
 how much it may contribute to the decep- 
 tion both of buyer and seller. To that 
 end will be shown the use of the sizes in 
 discovering a well or an ill made brilliant. 
 For example, suppose two stones of six 
 carats weight each, the one a well-made, 
 the other an ill-made stone ; the first will 
 tally in all circumstances with No. 20, of six 
 carats weight ; and the last may be loaded 
 with undue substance, by which means its 
 expansion may not exceed one of five, or 
 four carats weight. If any brilliant be so 
 circumstanced, it is to be valued only as it 
 
DIAMONDS AND PEARLS. 19 
 
 agrees with any of the same expansion in the 
 list, allowing for the expense of rectifying ; 
 because, whatever substance, or weight, it 
 carries beyond what its size demands, de- 
 stroys, in proportion to such excess, the 
 beauty of its make, and its true spirit and 
 lustre. And here may be seen the differ- 
 ence it would make to a purchaser, who 
 may be induced to give the price that a 
 well-made stone of six carats weight de- 
 mands, for one whose expansion may not 
 exceed that of five, or four carats weight. 
 For example, a stone of six carats weight, 
 by the rule before laid down, is worth 
 
 f s. d. 
 
 288 
 
 One of five carats - 200 
 
 One of four carats - 128 
 
 If the difference be so great in the in- 
 stance given, how much greater must it be in 
 regard to stones of larger weights ; and as 
 that may be easily known by the same me- 
 thod of inquiry, no other instance need be 
 here given. 
 
 Since, then, so great a deception may arise 
 
20 A TREATISE ON" 
 
 from the ill manufacture of diamonds, the 
 great use of the sizes in discovering such, 
 evidently appears. And, as the attaining a 
 right knowledge of the true make of dia- 
 monds will be found, of all other circum- 
 stances, the most necessary in arriving at 
 their value, some remarks are here made, 
 by which the reader is informed in what 
 manner the defects of ill-made brilliant dia- 
 monds will appear. To that end, an in- 
 stance is given of a stone of six carats weight, 
 which is but of the expansion of one of five, 
 carats. It will partake, more or less, of all 
 the following defects. Either it will be 
 deeper than a stone of five carats, or, if not 
 deeper, its table and collet will be larger, 
 and that will render it blocky, by the sides 
 being too upright ; or it will be left too thick 
 at the girdle, before the small work (which 
 means the star and skill fassets) is performed ; 
 and, if such thickness be sufficiently reduced, 
 that is, so as to be consistent with safety 
 in setting, the skill fassets will be executed 
 in an obtuse or blunt manner, and that will 
 cause an undue swelling in the stone ; or it 
 may, after all, be left too thick at the girdle. 
 
DIAMONDS AND PEARLS. 21 
 
 A stone thus made will unavoidably be of 
 an ill form, and be rendered lifeless and 
 dull ; which cannot be rectified without the 
 loss of its super-abounding weight, which 
 will reduce it to five carats ; and therefore 
 it is to be valued only as one of five carats. 
 And in case a stone, weighing six carats, 
 should tally only in size with one of four ca- 
 rats, these defects will be proportionably in- 
 creased, to the still greater prejudice of the 
 stone ; and therefore it will be purchasing 
 deformity at the price of beauty. 
 
 Of the Method of manufacturing, and valuing, 
 Spread Brilliants. 
 
 CONCLUDING it unnecessary to add any- 
 thing farther on the head of full-substanced 
 and over- weighted brilliants, the next thing 
 that requires notice, is, the method of 
 manufacturing and estimating spread bril- 
 liants. And as to the method of making 
 them, to do it in the most complete man- 
 ner, they must be proportioned, as in the 
 c 2 
 
22 A TREATISE ON 
 
 case of full-substanced ones, i at the up- 
 per, or table side, and $ at the under, or col- 
 let side ; and whatever be the diameter of 
 their tables, that of their collets must be i 
 thereof. The small work is to be performed 
 in the same manner as is practised in full- 
 substanced stones. This is all that is neces- 
 sary to be taken notice of, in regard to their 
 manufacture. But, previously to the method 
 of valuing them, the following observation 
 may be suggested : that, as sufficient rea- 
 sons have been given to make it appear that 
 brilliants may be injured in their shape and 
 true beauty by a super-abounding of weight, 
 so, on the contrary, it will appear, that if 
 they do not carry their true or full-substance 
 they will be injured in both these circum- 
 stances ; by reflecting on the consequence of 
 rendering them very thin or spread, which 
 has frequently been carried to so great an 
 excess, as to deprive them of the benefit of 
 workmanship; for the work must necessarily 
 be so flat, as to cause such stones to be faint 
 and languid in lustre, and thereby less 
 worthy of esteem in proportion to such ex- 
 cess. Notwithstanding which, it will be 
 
DIAMONDS AND PEARLS. 23 
 
 found, that in past times, instead of valuing 
 the weight of such wrought diamonds less 
 on that account, it has been valued the more ; 
 merely for the sake of their making a showy 
 appearance. To which may be added, that 
 all such stones are more liable to receive in- 
 jury by blows, falls, or hard pressure, than 
 full-substanced ones. 
 
 Here it is necessary to explain what is 
 meant by excess, because it must be allow- 
 ed, that some stones are so formed by nature 
 as not to be capable of being manufactured 
 by art into any other than spread brilliants, 
 without too great a waste of the diamond 
 species. Therefore, it may be laid down as 
 a fit rule, to include under that denomina- 
 tion (viz. of excess) all spread brilliants ex- 
 panded beyond the size of full-substanced 
 ones of double their weight : and such are 
 
 O ' 
 
 to be valued only as they may be supposed 
 to weigh, if reduced to this standard. 
 
 It remains to show in what manner spread 
 stones are to be valued ; which is, as full- 
 substanced ones are of the same weight, si- 
 milar in all other circumstances. And they 
 are to be so valued, on account of their ex- 
 
24 A TREATISE OX 
 
 pansion to the degree above mentioned ; for 
 it must be admitted, that the spaciousness of 
 their appearance to that degree counter-ba- 
 lances the deficiency of lustre, owing to their 
 want of substance. And this is all that can 
 be offered in justification of so valuing them, 
 which carries the appearance of partiality 
 rather in their favour than disfavour; espe- 
 cially in regard to such as are of the greatest 
 expansion within the limits mentioned ; con- 
 sidering, that full-substanced stones have all 
 the advantages that both nature and art can 
 bestow. 
 
 Of Rose Diamonds. 
 
 HERE it is to be observed, that nothing 
 can more perpetuate rose diamonds in 
 the esteem they have hitherto had in the 
 world, than maintaining the truth of their 
 manufacture. Nor was it ever more fit 
 to be recommended than at present, on 
 account of the corrupt taste that has of late 
 prevailed, in converting rose diamonds into 
 brilliants, under pretence of rendering them, 
 
DIAMONDS AND PEARLS. 25 
 
 by that means, a more beautiful and excel- 
 lent jewel. This has frequently been done, 
 to the great prejudice of their value, by les- 
 sening the weight and expansion they bore 
 in their preceding state ; and they have fre- 
 quently been more injudiciously manufac- 
 tured in the new species, than they were in 
 the old. This will appear to have been of- 
 ten the case, by the upper part of such stones 
 not carrying a true proportion of the sub- 
 stance of the stone; which of course ren- 
 ders the upper part flat, and the table of an 
 immoderate extent ; so that the side-work, or 
 bezil, appears but as a narrow border. This 
 method of working has been introduced 
 for the sake of preserving the expansion 
 and weight of such stones, which unavoid- 
 ably would be more reduced, if they were 
 allowed their true proportion of top : which 
 reduction, both of their weight and expan- 
 sion, will appear ever necessary to be done, 
 to render such stones complete spread bril- 
 liants ; for such only are they capable of 
 being manufactured into. 
 
26 A TREATISE ON 
 
 Of the Impropriety of transforming well-wrought 
 Hose Diamonds into Brilliants. 
 
 FROM what has been observed, it will 
 appear, that no rose diamonds are proper 
 subjects of this metamorphosis, but such 
 only as are over-weighted ; and of such, 
 those are the most proper subjects of the 
 metamorphosis which have the base, or gir- 
 dle, too thick. The over weight will be 
 discovered by the sizes hereafter mentioned. 
 To convert any rose diamond, not so cir- 
 cumstanced, to a brilliant, will be shown to 
 be a practice not founded in reason ; and 
 which carries in it the appearance of an at- 
 tempt to depreciate this ancient and spa- 
 cious manufacture of diamonds, in order to 
 exalt a new one beyond its real and true 
 merit. 
 
 For it will be found, that a complete rose 
 diamond will be more expanded than a 
 complete brilliant of the same weight, and 
 proportionably so in regard to spread stones ; 
 therefore, as it has been shown that an in- 
 crease of expansion is substituted in the room 
 
DIAMONDS AND PEARLS. 27 
 
 of depth, or substance, in brilliants, the same 
 is to be admitted in regard to rose diamonds, 
 provided their expansion does not exceed 
 the limits prescribed in the case of spread 
 brilliants. 
 
 And if it be admitted, as some have as- 
 serted, that there is a superior excellency in 
 brilliants, what must be the consequence, 
 but that rose diamonds must sink in their 
 value, to the great prejudice of the most no- 
 ble and ancient families, who are greatly 
 possessed of them, as being a more ancient 
 jewel than brilliants ; but, on the contrary, 
 it will appear that rose diamonds, when truly 
 manufactured, are not inferior to brilliants, 
 all circumstances considered. 
 
 Of the Form of a Rose Diamond. 
 
 SOME observations are now to be made 
 concerning their form. Their being called 
 rose diamonds probably took its rise from 
 their shape, in some measure, resembling 
 that of a rose-bud before it expands its 
 
28 A TREATISE ON 
 
 leaves. They appear in a kind of semi-glo- 
 bular form, only terminating in a point at 
 the top ; which form, and likewise the 
 work, or facets thereof, covering the whole 
 face of the stone, being more equal, exhibit 
 a more even display of beauty than a bril- 
 liant, whose lustre is derived from the an- 
 gles, or facets, of the sides only. And as 
 their angles are larger than those of a bril- 
 liant, they throw forth more copious rays ; 
 the lustre of which appears to be equivalent 
 to the sparkling vigour of the smaller, and 
 more numerous angles of a brilliant. 
 
 The fitness of asserting the dignity of the 
 rose-diamond manufacture having been 
 shown, the manner in which it is to be per- 
 formed is next to be pointed out. But first, 
 it is necessary to lay down what is requisite 
 to constitute a complete rose diamond. A 
 round or circular stone, is found the fittest 
 for that purpose ; because its form is the 
 most, beautiful, and productive of more vigour 
 than any other shaped stone ; which arises 
 from its admitting of more equal and better 
 connected facets than other shaped stones 
 will allow of. And for this further reason : 
 
DIAMONDS AND PEARLS. 29 
 
 that the same substance and manner of pro- 
 portioning, which render them most com- 
 plete, will render stones of any other shape 
 as beautiful as their forms will admit. The 
 right substance, proportions, and manufac- 
 ture of a circular rose diamond, are as 
 follow. 
 
 Of the Manufacture of a Rose Diamond. 
 
 THE depth of the stone from the base to 
 the point, must be half the breadth of the 
 diameter of the base of the stone ; and the 
 diameter of the crown must be of the 
 diameter of the base ; and the perpendicular 
 from the base to the crown, must be S of the 
 depth of the stone ; and then the lozenges, 
 which appear in all circular rose diamonds, 
 will be equally divided by the ribs that form 
 the crown. The upper angles, or facets, 
 will terminate in the extreme point of the 
 stone, and the lower in the base or girdle. 
 
 In the sixth plate, there are four draughts 
 of rose diamonds manufactured by the be- 
 fore-mentioned rules. The first is a side- 
 
30 A TREATISE ON 
 
 view of a circular shape. The second, an 
 horizontal view of the same. The third, an 
 oval. The fourth, a drop. Their several 
 parts are explained by the first and second 
 draughts. As to the first, a, is the point ; 
 bj the crown ; c, the girdle. The upper 
 triangles, or facets, show half the work of 
 the crown ; the under triangles, half the side. 
 As to the second draught, the common in- 
 tersection of the six cross lines meeting in 
 the centre of the draught, is the point ; the 
 lines that form the hexagon, and the trian- 
 gles within it, compose the crown; the tri- 
 angles without the hexagon compose the 
 sides ; the outlines show the girdle. All 
 lines in the draughts are called ribs in dia- 
 monds, except what express the girdles. 
 These draughts are representations of rose 
 diamonds of 36 carats weight each, and may 
 be of perpetual use to give a right idea of 
 their proper figures and workmanship. 
 
DIAMONDS AND PEARLS. 31 
 
 Of the Sizes of Rose Diamonds, and their Use in 
 discovering ill- wrought Ones. 
 
 IN the following plates, VII. VIII. IX. 
 
 X., is exhibited a list of 55 draughts of 
 circular rose diamonds, from one carat 
 weight to an hundred carats, which are so 
 many tests to prove the truth, or defects, of 
 any manufactured stone of that kind. Their 
 use, as in the case of brilliants, will be shown 
 in proving a rose diamond to be either truly 
 made, or not. For example, suppose one 
 of five carats weight ; if it be truly made, 
 it will be as expanded at the base, or girdle, 
 as No. 18, of five carats, and the size of the 
 crown will also agree therewith ; its depth 
 will be likewise half its diameter or breadth. 
 But if it be basely made, and left loaded 
 with undue weight, its expansion at the base 
 may not exceed one of above three, or four 
 carats weight. Such a stone, according to 
 the degree in which it falls short of its just 
 size, will partake of some, or all the follow- 
 ing defects. Either its depth, from the base 
 to the point, will exceed the rule; or, 
 
32 A TREATISE ON 
 
 though it should not be too deep, its sides 
 below the crown may be too upright, which 
 will be discovered by the crown exceeding 
 its proper extent, and that will consequently 
 cause a flatness from the crown to the point ; 
 or the crown may be situated too high ; if so, 
 the size of the crown may not exceed its just 
 extent, but then it will occasion an increased 
 flatness of the crown, and produce an extra- 
 vagant depth below it ; or the girdle may be 
 left too thick. If any rose diamond is made 
 after this manner, it will, according to the 
 degree in which it is thus defective, be in- 
 jured in its shape, spirit, and lustre ; and 
 therefore is not to be valued by its weight, 
 but only as it agrees in size with any in the 
 list ; for the same reasons as are given in the 
 like case of brilliants. 
 
 Of the Method of manufacturing and valuing 
 Spread Rose Diamonds. 
 
 THE next thing to be regarded, is the 
 manner of making and valuing spread rose 
 

 DIAMONDS AND PEARLS. 33 
 
 diamonds. As to the manner of making 
 them ; what is necessary to be observed, 
 is, that their crowns must be of such an 
 extent, and placed in such a situation, as to 
 prevent any disproportionate flatness in the 
 crown, and unequal division of the lozenges : 
 and, that they be made as thin at the girdle 
 as is consistent with safety in setting them. 
 This is all that is necessary to be observed on 
 that head. As to valuing them ; the same 
 method is to be observed as in the case of 
 spread brilliants in all respects. 
 
 Note This article of making spread rose 
 diamonds, is as necessary to the same ends 
 and purposes, as the manufacture of spread 
 brilliants ; inasmuch as they occupy thinner 
 matter than brilliants can. 
 
 From what has been said of rose dia- 
 monds, it seems evident, taking in all cir- 
 cumstances, that they deserve as much esteem 
 and regard as brilliants, and are entitled, 
 weight for weight, to an equal value : some 
 persons with us, and those of great reputa- 
 tion for knowledge in diamonds, prefer the 
 former to the latter ; but, although this be 
 the opinion of particular persons, it seems no 
 D 2 
 
34 A TREATISE ON 
 
 better grounded than that of others, in giving 
 brilliants the preference ; for the same con- 
 sequence must follow from thence to the 
 possessors of brilliants, as has been men- 
 tioned concerning the possessors of rose dia- 
 monds ; which was, that if brilliant dia- 
 monds were preferred to rose diamonds, 
 these latter must sink in their value ; so, on 
 the contrary, if rose diamonds are preferred, 
 brilliants must sink in their value ; and if 
 they are equally esteemed and valued, as it 
 appears they ought to be, it will conduce to 
 the saving of weight, that a bias to either mode 
 of working will unavoidably occasion. 
 
 The next thing that falls under consider- 
 ation, is the methods of valuing diamonds. 
 
 The first Method of valuing Wrought Diamonds, 
 in Conjunction with Rough Diamonds, out of 
 which they are supposed to be wrought. 
 
 AN example is here given to show in what 
 manner the value of a manufactured, or 
 wrought diamond, of one carat, is to be 
 found, upon the principle advanced, sup- 
 
DIAMONDS AND PEARLS. 35 
 
 posing rough diamonds to be valued at two 
 pounds per carat. 
 
 The weight of such a stone must be dou- 
 bled (on account of half being supposed to 
 be lost in working it) which is considered as 
 its original weight, making two carats ; then 
 multiply that weight into itself, which 
 squares it, and makes four ; lastly, multiply 
 the four by two, that produces eight pounds, 
 which is the value of a stone of one carat, 
 wrought or polished, and is equal to the va- 
 lue of the rough diamond of two carats, out 
 of which it is supposed to be made. This 
 single instance is here given to show the va- 
 lue of rough diamonds in the price of 
 wrought ones; and as a farther explanation 
 of the rule of valuing them, and previous to 
 the offering any other, it is to be observed, 
 that although two pounds is laid down as 
 the general price of rough diamonds, it is 
 nevertheless to be understood, that rough 
 diamonds differ in their value, according to 
 their different degrees of perfection or im- 
 perfection, and according to the loss of 
 weight they may be supposed to sustain in 
 being truly wrought ; as it is well known, 
 
38 A TREATISE ON 
 
 that some will lose abundantly more than 
 others, arising from their ill forms and other 
 defects that may attend them, which defects 
 are so numerous and difficult to be expressed, 
 that what may be said of them would proba- 
 bly not be understood, but by the most expe- 
 rienced traders and manufacturers of them. 
 This consideration, and that of its being but 
 of little concern to the public, prevent my 
 saying anything more relating thereto. 
 
 In farther explaining the principle of va- 
 luing wrought diamonds, three other in- 
 stances, besides that already given, will be 
 offered, to show the operation of the princi- 
 ple in coming at the value of wrought dia- 
 monds, which, it is judged, will be sufficient 
 in all other cases in this way of proceeding. 
 After that will be offered three more of the 
 same weight, in a different manner of pro- 
 ceeding, but to the same end. 
 
 Here it may be proper to hint, that all 
 the instances that will be given, are founded 
 upon the price of rough diamonds in general, 
 being put at two pounds per carat, viz. good 
 and bad blended together, as has been before 
 noticed ; so that two pounds is the price of 
 
DIAMONDS AND PEARLS. 37 
 
 the middle sort only. And it is also to be 
 remembered, that in manufacturing, half the 
 weight is supposed to be wasted. And as 
 mistakes may be made in calculating the va- 
 lue of particular diamonds, in the manners 
 hereafter prescribed, it is here noted, that 
 the prices of diamonds, from one of one ca- 
 rat to one of an hundred carats, of this de- 
 gree of goodness, are contained in plates XI. 
 XII. XIII. XIV. XV. XVI.; which will 
 prove the truth or falsity of any calculation : 
 and it is also to be observed, that the ex- 
 pense of manufacture, or workmanship, is 
 excluded in all the instances that will be 
 given on this occasion, the reasons of which 
 will hereafter appear. 
 
 Now follow the three other instances pro- 
 posed, to explain this first method of finding 
 the value of any wrought diamonds. 
 
 The first Instance. 
 
 To find the value of one of five carats 
 weight, the weight must be doubled, on ac- 
 count of half being supposed lost in working 
 it ; that replaces its original weight, which 
 
38 A TREATISE ON 
 
 makes ten carats ; then multiply ten by ten, 
 that squares the weight, and makes one 
 hundred carats ; and, lastly, the one hun- 
 dred must be multiplied by two pounds, the 
 price of one carat ; that produces two hun- 
 dred pounds, and is the value of a wrought 
 stone of five carats, and the price of the dia- 
 mond when rough. 
 
 EXAMPLE. 
 
 10 Carats 
 Multiplied by 10 Pounds 
 
 Makes 100 . 
 
 Multiplied by 2 Pounds 
 
 Makes 200 
 
 Second Instance. 
 
 To find the value of one of five carats *, 
 the weight must be doubled, that makes 
 ten | ; next multiply that weight by four, 
 to bring it into fourths, or grains, which 
 makes forty-one ; then multiply forty-one by 
 

 DIAMONDS AND PEARLS. 39 
 
 forty-one, that makes one thousand six hun- 
 dred and eighty-one, the square of the 
 weight in sixteenths; therefore divide the 
 one thousand six hundred and eighty-one by 
 sixteen, that brings it again into carats, and 
 makes one hundred and five carats T ^ ; 
 which multiplied by two pounds, produces 
 210/. "2s. 6d. and is the value of the stone, 
 rough or wrought. 
 
 EXAMPLE. 
 
 Carats 
 101 
 
 4 
 
 41 
 41 
 
 41 
 164 
 Carats 
 
 16) 1681 (105 T V 
 2 
 
 210 2 6 
 
40 A TREATISE ON 
 
 Third Instance. 
 
 To find the value of one of five carats J ; 
 the weight doubled is ten carats i ; reduce 
 that weight into grains, by multiplying it by 
 four, that makes forty-two ; then multiply- 
 ing forty-two by forty-two, that makes one 
 thousand seven hundred and sixty-four, 
 the square of the weight in sixteenths ; 
 which divide by 16, that brings them again 
 into carats, and makes one hundred and ten 
 carats and &; which multiply by 2/., that 
 produces 220/. 10s. and is the value of the 
 stone, rough or wrought. 
 
 EXAMPLE. 
 
 10J 
 4 
 
 42 
 42 
 
 84 
 168 
 
 Carats 
 
 16) 1764 (HOT 4 * 
 2 
 
 220 10 
 
DIAMONDS AND PEARLS. 41 
 
 The second Method of valuing Wrought Dia- 
 monds, in Conjunction with the Rough Dia- 
 monds, out of which they are supposed to be 
 wrought. 
 
 First Instance. 
 
 To find the value of a diamond of five 
 carats weight, as in the foregoing cases, 
 so in this, the weight must be doubled ; 
 that makes ten carats. As a rough diamond 
 of one carat is valued at two pounds, every 
 carat in this stone accumulates ten times 
 that value ; and so every carat in this stone 
 is to be valued at twenty pounds ; therefore 
 multiply ten carats by twenty pounds, that 
 will produce two hundred pounds, and is 
 the value of the stone, rough or wrought. 
 
 EXAMPLE. 
 
 10 Carats 
 Multiplied by 20 
 
 Makes the total 200 Pounds 
 
 E 
 
42 A TREATISE ON 
 
 Second Instance. 
 
 To find the value of one of five carats 
 e ; the weight doubled makes ten carats ; 
 next reckon that weight in the foregoing 
 manner, that makes every carat in this 
 stone worth twenty pounds, ten shillings : 
 so first multiply ten carats by twenty pounds, 
 that makes two hundred pounds ; then mul- 
 tiply ten carats by ten shillings, that makes 
 one hundred shillings, or five pounds ; next 
 add the value of a fourth of a carat at the 
 rate of 20/. 10s., that makes 5/.2s.6d.; lastly, 
 cast up these three sums, the total will be 
 210/. 2s. 6d. and is the value of the stone, 
 rough or wrought. 
 
 EXAMPLE. 
 
 10 Carats 
 
 Multiplied by 20 Pounds 
 
 Makes 200 Pounds 
 
 10 cts. mult, by 10s. makes 5 
 The value of J of a carat 1 ~ 9 
 at 20/. 10s. is 
 
 Makes the total 210 2 6 
 
DIAMONDS AND PEARLS. 43 
 
 Third Instance. 
 
 To find the value of one of five carats i ; 
 the weight doubled makes ten carats 2 ; 
 reckon that weight as in the two other cases, 
 that makes every carat in this stone worth 
 twenty-one pounds : so multiply ten carats 
 by twenty-one pounds, that makes 210/., then 
 add the value of the half carat at twenty- 
 one per carat, that makes 10/. 10<y. ; lastly, 
 add the two sums together, the total will 
 be 220/. 10s. and is the value of the stone, 
 rough or wrought, 
 
 EXAMPLE. 
 
 10 Carats 
 Multiplied by 21 
 
 Makes 210 
 
 The value of the I carat? ,~ ,~ 
 added, which is 5 
 
 Makes the total 220 10 
 
44 A TREATISE OX 
 
 The instances that have been given of two 
 methods, for finding the value of wrought 
 diamonds, as they stand connected with the 
 rough (out of which they are supposed to be 
 made) it is apprehended, are a sufficient ex- 
 planation of the principle for valuing rough 
 and wrought diamonds ; and prove its being 
 founded on reason. 
 
 Of the Method of valuing Wrought Diamonds, 
 exclusive of any Regard to Rough Diamonds. 
 
 As instances have been given of two dif- 
 ferent methods of attaining the value of 
 wrought diamonds, in which cases the value 
 of rough diamonds of double their weights 
 have been jointly considered, they being 
 supposed to be made from such rough 
 diamonds ; three instances of manufactured 
 diamonds, of the same weights, will be now 
 offered, to show in what manner their value 
 may be found, exclusive of any regard to 
 rough diamonds : and as the last method 
 appears the shortest, and most easy to be 
 
DIAMONDS AND PEARLS. 45 
 
 understood, that method will be made use of 
 on this occasion. 
 
 This is to be known by applying the price 
 they bear manufactured, which has been 
 shown, viz. that as rough diamonds are va- 
 lued at two pounds per carat, a wrought 
 diamond of one carat is worth eight pounds ; 
 so to find the value of a stone of that degree 
 of goodness, whatever number of carats are 
 contained in such a diamond, each is to be 
 valued at eight pounds ; and whatever sum 
 they make, must be multiplied by the weight 
 of the diamond. 
 
 The instances are as follow : 
 
 First Instance. 
 
 To find the value of such a diamond of 
 five carats weight, reckon every carat at 8 
 pounds ; then multiply 5 carats by 8 pounds, 
 that makes 40 pounds ; so every carat is to 
 be valued at 40 pounds ; then multiply 5 
 by 40, that produces 200/. and is the value 
 of such a diamond. 
 
 E2 
 
46 A TREATISE ON 
 
 EXAMPLE, 
 
 5 Carats 
 Multiplied by 40 Pounds 
 
 Makes the total 200 
 
 Second Instance. 
 
 To find the value of one of five carats j, 
 at the rate of 8 pounds per carat ; multiply 
 5 by 1, that makes 40 ; then add to that 
 the value of J of 8 pounds, that is 1 pound ; 
 so the value of every carat in this stone, is 
 41 pounds; then multiply 5 by 41, that 
 makes 205 pounds ; next add the value of 
 J of 41 pounds, that makes 51. 2s. 6d. 
 These two sums cast up, produce 21 01. 2s. 6d. 
 that is the value of the diamond. 
 
DIAMONDS AND PEARLS. 47 
 
 EXAMPLE. 
 
 5 Carats 
 Multiply by 41 
 
 Makes 205 
 
 To which is to be added "1 
 
 the value of } of 4U 1 526 
 
 which is J 
 
 Makes the total 210 2 6 
 
 Third Instance. 
 
 One of five carats J ; the value of each 
 carat is 42 pounds ; multiply 5 by 42, that 
 makes 210 Pounds 
 
 Then add the value ? i n i n 
 
 of i of 42, which is $ 
 
 Makes the total 220 10 
 
48 A TREATISE ON 
 
 Of the highest and lowest Price of Rough and 
 Polished Diamonds. 
 
 HAVING explained the different methods 
 of finding the value of rough and wrought 
 diamonds, of the middle sort, the first being 
 rated at two pounds per carat, the second 
 at eight pounds : as rough and polished 
 diamonds may be of a higher and lower 
 value, it remains to show what may be the 
 highest and lowest of each. 
 
 First I shall speak of rough diamonds, 
 and shall suppose three prices ; for instance, 
 one pound, two pounds, three pounds ; the 
 middle being two pounds, there appears an 
 advance of one pound above the middle 
 price, and a fall of one pound below ; which 
 is a deviation of fifty per cent, each way, 
 and makes the worst sort be but j the value 
 of the finest. 
 
 That the two extreme prices naturally 
 proceed from that of the middle price, I 
 shall endeavour to prove ; and in order 
 thereto, I shall first show, that no rough 
 diamond, which is not worth one pound per 
 

 DIAMONDS AND PEARLS. 49 
 
 carat, ought to be manufactured; because 
 all that are of less value must be very de- 
 fective, carrying many, or all of the follow- 
 ing blemishes : fouls, or stains, specks, flaws, 
 being veiny, craggy, ill -formed, and of an ill 
 colour; which, consequently, must obstruct 
 and defeat the purposes of manufacture ; for 
 with all that art can do, they will be void of 
 lustre, which will sink them below the rank 
 of a jewel. 
 
 Next, it is to be observed, that all under 
 that value will sell for as much, to be used 
 in cutting and forming the better sort, as any 
 one can afford to give for them, with the 
 view of manufacturing them ; for the ex- 
 pense of workmanship must be the same as 
 for better stones, if well done ; and if not 
 well done, it will add to the other defects ; 
 and the loss of weight must be greater than 
 what attends better stones, by its being fre- 
 quently necessary to discharge or lessen the 
 defects before mentioned : indeed, when a 
 stone of a very large size falls in the way, it 
 may be thought worth the expense of work- 
 ing, as its size may recommend it; these 
 being rarely to be met with, but not as orna- 
 
50 A TREATISE ON 
 
 mental to any thing ; and such may be va- 
 lued below four pounds per carat, as the 
 buyer and seller may agree on. 
 
 As it cannot but appear, that no rough 
 diamond ought to be wrought that is not 
 worth one pound per carat, this must be al- 
 lowed the lowest price of rough diamonds, 
 worthy of manufacture ; which, as has been 
 observed, is half the value of the middle 
 price ; so allowing as much advance above 
 it, makes the price of the finest rough dia- 
 monds worth three pounds per carat. 
 
 This being admitted, it shows that manu- 
 factured diamonds, of the worst sort, are 
 worth four pounds per carat, and the finest 
 twelve pounds per carat; and this, probably, 
 will be thought scope sufficient to employ 
 speculation and judgment; and if the value 
 of rough diamonds should rise or fall, the 
 middling price must be always that which 
 the whole was valued at, good and bad 
 blended together ; and as many prices as 
 will lie between those of the lowest price 
 and those of the middle price, so many must 
 be admitted above the middle price, and 
 that will determine the highest price : or, 
 
DIAMONDS AND PEARLS. 51 
 
 in other words, whatever the worst are va- 
 lued at below those of the middle sort, so 
 much must the finest be valued at above the 
 middle sort. And, therefore, the value of 
 all diamonds is to be adjusted within the li- 
 mits of the extreme prices. 
 
 Remarks on Brazil Diamonds. 
 
 FROM the want of this knowledge, and 
 the rule of valuing diamonds, has arisen 
 the wide difference of jewellers' sentiments 
 concerning their just and natural value; 
 the ill effects of which difference to indivi- 
 duals I shall be silent about, that having 
 been too sensibly felt to need any remarks ; 
 but proceed to show what an effect it has 
 had, in times past, on this important pro- 
 perty in general. 
 
 In the year 1733, rough diamonds were 
 not worth twenty shillings per carat ; in the 
 year 1735, not worth thirty shillings; in the 
 year 1742, not worth more than thirty shil- 
 lings per carat ; all which may clearly be 
 
52 A TREATISE ON 
 
 made appear, from public sales in the be- 
 fore-mentioned years. Catalogues of them 
 I have preserved, on which I have made par- 
 ticular remarks, and shall be ready to show 
 them on any proper occasion. I have been 
 the more careful to preserve them, believing 
 there never will be the like exhibited again ; 
 and the farther cause of publishing these 
 facts, is to show, that if the traders had 
 better known how to value diamonds at that 
 time, and had been better informed of the 
 real cause of so great a plenty as then ap- 
 peared, they would not have discovered so 
 great a consternation as then possessed them ; 
 which occasioned many, even of the most 
 capital traders in London, to believe, that 
 diamonds were likely to become as plenty 
 as transparent pebbles; and they were so 
 far influenced by this opinion, that most of 
 them refused to buy diamonds on any terms. 
 The adventurers were chiefly persons of 
 low circumstances, on which account the 
 Lisbon merchants dreaded any returns made 
 them in diamonds, or any sent them for sale ; 
 being forced to deal with such persons upon 
 
DIAMONDS AND PEARLS. 53 
 
 credit, and at any price that these purchasers 
 were pleased to give for them. 
 
 One of the most considerable Portugal 
 merchants, with whom I dealt, told me, in 
 the month of January, 1733-4, at which time 
 I bought a parcel, to the amount of seven 
 hundred and fifty pounds, that he had been 
 forced (for want of more reputable buyers) 
 to sell and give credit for many hundreds of 
 pounds, to such as he would not have trusted 
 with five pounds cash ; and that he found 
 other merchants were in the like case : on 
 which account there were many large par- 
 cels returned to Lisbon, they not being able 
 to find buyers enough, even of this sort, to 
 take off their goods. 
 
 I shall here mention some other matters, 
 that arose in conversation at this time. This 
 gentleman observing me to be more exact 
 than others, in weighing the large stones of 
 the parcels I bought of him, and some of 
 other parcels, asked me the reason of it ; upon 
 which I told him, that no man who did not 
 know how to value diamonds in proportion 
 to their weight (whatever knowledge else 
 he might have of rough diamonds) could 
 
54 A TREATISE ON 
 
 be a proper judge of the value of any stone. 
 Upon which he was pleased to say, if I had 
 that secret, he apprehended I might get what 
 money I pleased. I told him, it could be 
 of no service to me till it became public, 
 and the world made sensible of the truth of 
 the principle. Upon this he said, he thought 
 it might be of great use to make it public ; 
 and asked, if 1 did not intend to communi- 
 cate it to the world. I told him, it was my 
 intention, when circumstances rendered it 
 more proper ; observing it would be by no 
 means proper then, as the public, and like- 
 wise the traders in them, were so apprehen- 
 sive of the Brazil mines producing an inex- 
 haustible store; judging from thence, the 
 world would scarcely think diamonds worth 
 any consideration, especially as jewellers so 
 undervalued them. 
 
 As this has been, and still is, in a less de- 
 gree, the state of the case in regard to dia- 
 monds, it may be proper to inquire, whether 
 it be fact, that these mines have produced 
 any diamonds ; or whether the diamonds 
 that have been sent from thence, be not such 
 as they procured by trade. 
 
DIAMONDS AND PEARLS. 55 
 
 Having many years past been very solici- 
 tous to know the truth of this matter, I have 
 spared no pains to come at as good a know- 
 ledge thereof as I could procure ; and what 
 information I have met with, I shall disclose. 
 
 In the year 1734, I had the pleasure of 
 being acquainted with a gentleman that had 
 been, but a few years before that time, go- 
 vernor of Fort St. George. He told me, 
 upon my talking with him about the Brazil 
 mines, that he did not believe a tittle of the 
 report, and gave this as a reason for his dis- 
 belief of it; namely, that when he was at 
 Fort St. George, he was informed that the 
 Brazil people had long carried on a secret 
 trade with the India people at Goa, for dia- 
 monds, and was assured they had a vast 
 stock, but not very fine, they generally 
 choosing to buy the more indifferent sort, 
 for the sake of cheapness ; and he said, what- 
 ever quantity came from thence would not 
 alter his opinion, in regard to the value of 
 what he was possessed of, nor would he abate 
 of the price they were valued to him at, in 
 India ; saying, they only knew how to value 
 diamonds. In this resolution he persisted to 
 
56 A TREATISE ON 
 
 his death, which happened but a few years 
 since. Some of these diamonds he sold be- 
 fore his death, at his own price ; and he 
 then said, it was his opinion, that their send- 
 ing their diamonds to Lisbon, was not a 
 matter of choice, but necessity ; being forc- 
 ed thereto, in order to raise a large sum of 
 money to discharge great arrears of indulto, 
 which they then owed the king of Portugal ; 
 and the same has, since that, been said by 
 others. And, moreover, it has been said, 
 that the late king having been made ac- 
 quainted that they were greatly in debt to 
 their European correspondents, he insisted 
 upon their sending a sufficient quantity to 
 discharge those debts ; and when they came 
 to Lisbon, in order to give immediate satis- 
 faction to the merchants, it was said, the 
 king ordered them to be sold in a public 
 manner, for the sake of expedition; and 
 some have thought it was done out of resent- 
 ment to his Brazil subjects, for their using 
 him and the European merchants ill ; he 
 knowing they had it in their power, long 
 before, to have remitted these diamonds. 
 Another circumstance had like to have 
 
DIAMONDS AND PEARLS. 57 
 
 escaped my notice ; which is, that it has 
 been also reported here by persons of figure 
 and unquestionable veracity, who happened 
 to be at Fort St. George, when it was re- 
 ported that the Brazil mines had furnished 
 Europe with a great quantity of diamonds 
 very cheap, that the India people laughed, 
 and said, it would not alter their price. 
 
 From what has been observed, there 
 seems room to think, that these diamonds 
 are the effect of the king of Portugal's sub- 
 jects' trade, and not the produce of his Bra- 
 zil mines; for it cannot be thought any 
 prince would have countenanced such a dis- 
 advantageous method of disposing of the pro- 
 duce of his own mines, as was practised in 
 getting rid of them, notwithstanding any re- 
 dundancy; on the contrary, that he would 
 have restrained the sending any quantity, 
 that must tend to sink their value, which is 
 always carefully avoided by the India people. 
 And if it were true that his Brazil mines 
 so abounded with diamonds, they must be 
 come at with a great deal less expense than 
 attends the search of diamonds in India; 
 and of course he must become the richest 
 
 F2 
 
58 A TREATISE ON 
 
 prince in Europe : for it would ue an addi- 
 tional employment for his Brazil subjects, 
 in consequence of which his commerce must 
 be greatly increased ; inasmuch as we should 
 always encourage it, rather than that of the 
 India trade, on account of our purchasing 
 diamonds in India chiefly for bullion. And 
 can it be supposed a wise prince would dis- 
 regard a gift of Providence, so highly esteem- 
 ed by the eastern part of the world ? And 
 therefore the methods made use of, must 
 be supposed to proceed from the late king's 
 knowing they were the effects of trade ; if so, 
 it cannot but be judged a wise and just step 
 in him, to force them to discha/ge their obli- 
 gations to himself and their correspondents, 
 knowing they could procure no advantage 
 to them, by lying in their hands as a dead 
 stock. Besides, trading in diamonds has 
 been disallowed by the late king; and to 
 conceal it from his knowledge, is supposed 
 to be the reason of their giving out, that the 
 diamonds they were formerly possessed of 
 were the produce of his Brazil mines ; and 
 to make it the more plausible, they suffered 
 it to be reported, that they were of a dif- 
 
DIAMONDS AND PEARLS. 59 
 
 ferent nature, as well as worse than India 
 diamonds. 
 
 Upon this occasion I will venture to say 
 (from critical observations in an extensive 
 commerce and manufacture of both) that 
 there has not appeared to me a circum- 
 stance, in those called Brazil diamonds, that 
 I have not found in India diamonds ; and 
 it is likewise noticed, that some years' cargo 
 from the Brazils have been as fine as any 
 year's cargo from India ; and that the small 
 diamonds have sold at as high a price as 
 ever was given for small India diamonds. 
 And it is also remarked, that what have of 
 late been brought from Brazil, we hear but 
 little of; more than their quantity yearly 
 lessens, notwithstanding their price is raised 
 more than treble of what they bore some 
 years ago. There are various sentiments 
 among traders concerning the cause of 
 it; but being much divided in their opi- 
 nions, I shall not trouble my readers there- 
 with ; not doubting but their sending so few 
 will appear to arise from their not being pos- 
 sessed of more. And, from hence may be 
 inferred, that they are interrupted in this 
 
60 A TREATISE ON 
 
 commerce, and deprived of the means of 
 procuring them as formerly ; which means 
 are supposed to have been their purchasing 
 them with Brazil gold, wherein the Brazil 
 mines are known to abound in a profuse de- 
 gree ; and in this sense it may be said, the 
 diamonds that we have had from thence are 
 the produce of the Brazil mines ; and if there 
 be a check, or an interruption thrown in the 
 way of this barter, we cannot expect to have 
 such quantities as formerly, although more 
 or less may always come from thence; which 
 has been the case before the great glut ap- 
 peared ; but they were not then called Bra- 
 zil diamonds, and what was brought from 
 thence was conducted with great secrecy : 
 and it is likely this trade will be continued, 
 from the circumstance of diamonds being so 
 
 o 
 
 portable a commodity, and what may be 
 conveyed with great secrecy, however strict 
 his Portuguese majesty's orders may be in 
 prohibiting thereof. As to the political 
 reasons for prohibiting this traffic, it is not 
 my province to meddle with that. 
 
 Amidst what has been said to show the 
 improbability of the Brazil mines having 
 
DIAMONDS AND PEARLS. 61 
 
 produced the diamonds, that of late years 
 have been placed to their account, the cir- 
 cumstance that has been before mentioned 
 deserves more than ordinary notice ; there- 
 fore I shall recite it again; which is, that 
 notwithstanding the India people knew what 
 despicable prices Brazil diamonds sold for in 
 Europe, in the before-mentioned years, they 
 kept up the price of their diamonds ; which 
 seems to prove they were the sellers of those 
 diamonds to the Brazilians, and serves to ex- 
 plain what they meant by laughing at the 
 report of the Brazil mines furnishing Europe 
 with diamonds, and their saying it would not 
 alter their price. 
 
 This conduct, surely, deserves the highest 
 applause ; for had they copied after the Bra- 
 zilians, this great article of wealth, by this 
 time, would have been reduced almost to 
 nothing ; the ill effects of which, words can- 
 not sufficiently express : the prevention of 
 this evil the India people must have the ho- 
 nour of. 
 
 To maintain as invariable a price of these 
 jewels as is possible, must be of the greatest 
 utility to the public ; which they appear to 
 
62 A TREATISE ON 
 
 be sensible of, from their past conduct ; but 
 there is more to be offered in proof of this. 
 
 It is attested by unquestionable authority, 
 that when they find a slack demand for dia- 
 monds, they always withdraw them; the 
 consideration of any quantity they may be 
 possessed of seems to be no motive with them 
 for abating their price ; which is believed 
 to arise from their supposing they have com- 
 petitors to subject them thereto ; and from 
 what has been observed, the truth of it can 
 scarcely be doubted ; and their manner of 
 trading with us seems to be a further proof 
 of it, which is thus : 
 
 They first find out what sorts are wanted, 
 and then show such goods and put their 
 price : if they are sold, they have their de- 
 mand ; for they suppose themsehres to be 
 the only judges of their value ; arid it does 
 not appear that any one has disputed the 
 truth of it. From hence it is, that diamonds 
 are sent here in bulces, which means parcels 
 of diamonds neatly tied up in muslins, and 
 sealed by the sellers of them ; which dia- 
 monds are generally bought here by the in- 
 voice, that is, are bought before they are 
 
DIAMONDS AND PEARLS. 63 
 
 opened ; it being always supposed they con- 
 tain their value which they were sold for in 
 India ; and the buyer here gives the mer- 
 chant such a profit as contents him. The 
 diamonds being thus bought, the buyer 
 opens the parcel, separates them, and then 
 values them separately as his judgment di- 
 rects; making to himself, likewise, such a 
 profit upon the whole parcel, as he thinks 
 proper. And as this is the case, it is refer- 
 red to the consideration of reflecting minds, 
 whether or no any man can properly judge 
 of the value of stones of different sizes and 
 properties, without some rule to direct his 
 judgment. As for the different properties 
 of diamonds, speculation, assisted by the 
 knowledge acquired in manufacturing dia- 
 monds, is the only guide ; but whether any 
 can judge of their value, regarding their 
 magnitude, is the thing in question. It 
 seems as if our traders thought the India 
 people were masters of some rule for that 
 purpose, by placing such confidence in them, 
 as it appears they do by this representation ; 
 and it is believed, when the European part 
 of the world are acquainted with the true 
 
64 A TREATISE ON 
 
 method of estimating diamonds, it will be 
 found, that the India people have generally 
 valued their large diamonds alike at all times, 
 let the demand for them vary as it may. 
 
 If that be the case, is not this issuing out 
 another staple commodity like that of gold 
 and silver? And although its value is not as- 
 certainable to so great an exactness as either 
 of those, by an assay, yet it may appear they 
 are reducible to as great a nearness in spe- 
 culation, as either of the other two. But 
 however beneficial this may be, the value oi 
 diamonds can never be at all settled in Eu- 
 rope, whilst we are amused with the notion 
 of the Brazil mines being productive of dia- 
 monds. How far it is the interest of these 
 parts of the world to be well informed of 
 the truth of this matter, is left to the consi- 
 deration of the public. 
 
 But suppose it should be remarked, that 
 although diamonds in India may at all times 
 be near the same value, it cannot be the case 
 in other parts of the world, arising from va- 
 rious circumstances : the chief cause of which 
 variableness in the price of diamonds, or any 
 jewels, in other parts of the world, cannot 
 
DIAMONDS AND PEARLS. 65 
 
 but be seen to be the disagreement in the sen- 
 timents of jewellers concerning the natural 
 value of them. But the extraordinary in- 
 stances in the late wars in Germany, will be 
 a farther proof of it ; inasmuch as it has been 
 told us by public papers, that not above 
 one-third or one-fourth of the money which 
 gems have cost, could be procured by way 
 of pledge or sale : indeed the avarice of the 
 buyers may have some share in occasioning 
 so great a loss. Does this prove the intrinsic 
 worth of jewels, so frequently talked of? Must 
 not this be a vast discouragement to great 
 personages from vesting themselves with this 
 property ? How fit, therefore, is it to ren- 
 der them as invariable in their price as the 
 nature of things will admit of; since they 
 possessed themselves thereof, not only for 
 personal ornaments, but also as articles of 
 solid treasure, to serve such emergencies as 
 have been noticed ? And it is known, that 
 there are some rough diamonds of great 
 price, as well as polished, in Europe, which 
 have been bought upon that principle. 
 
 Since it is thus, nothing can be a greater 
 inducement to persons of high station to 
 
 G 
 
66 A TREATISE ON 
 
 purchase diamonds, than rendering their va- 
 lue more staple. And as nothing can ac- 
 complish that so much as being well ac- 
 quainted with their true value, the follow- 
 ing method will be found the only way of 
 coming at that knowledge. 
 
 It appears from the reason of things, that 
 all large diamonds are to be valued accord- 
 ing to the rule advanced, by the price that 
 one of a carat bears, which is similar to a 
 stone, whose value you would know ; for as 
 you value the weight in a stone of one ca- 
 rat, so must you that of a stone of the same 
 properties, let the weight be what it may. 
 And as a farther proof of its being right, it 
 will be found, that jewellers, of the greatest 
 experience and knowledge, have generally 
 estimated diamonds as this rule directs, by 
 dint of sound judgment : and as the young- 
 er and less experienced must want some as- 
 sistance in this important concern, this will 
 put them in the right way, and by means 
 hereof the value of diamonds will be made 
 universally known ; as it lies in so narrow a 
 compass, as that of any one's making him- 
 self acquainted with the worth of a diamond 
 
DIAMONDS AND PEARLS. 67 
 
 of a carat weight ; which, it is presumed, 
 persons of good judgment cannot be at a 
 loss to know, let them be good, bad, or in- 
 different ; and that such will agree in their 
 sentiments concerning the value of a stone of 
 a carat weight, be it, as it may, to five or ten 
 per cent. 
 
 Of the Table of Prices of Diamonds. 
 
 THE next thing to be taken notice of, is 
 a table, which will be found in the llth, 
 12th, 13th, 14th, 15th, and 16th plates. 
 This table consists of the price of diamonds, 
 from one carat weight to an hundred carats; 
 formed upon the principle of valuing them 
 by the square of their weight, upon the sup- 
 position that the governing price of rough 
 diamonds, good and bad blended together, 
 is 2/. per carat ; so that 21. is to be reckoned 
 the mean or middle price, and will be found 
 of great use to prevent the trouble of calcu- 
 lating the price of every stone by the rule. 
 If any stone differs in its value from this mean 
 or middle price, whether higher or lower, so 
 
68 A TREATISE ON 
 
 much per cent, is to be added, or deducted, 
 as judgment shall direct. It may be observ- 
 ed, that the tables do not descend to six- 
 teenths of a carat; it is omitted for brevity's 
 sake, which may be supplied by casting up 
 any two adjoining prices, and then take the 
 half, that will give the prices of the inter- 
 mediate weight. For example : a stone of 
 one carat will be seen to be the first article 
 in the table, and to come to 8/. To find it 
 out by the rule, the method is to multiply 
 2 by 2, that makes 4, which is the square 
 of its weight ; then multiply 4 by 2/., the 
 price of one carat, that makes 8/. Here it 
 is to be remembered, that all the prices 
 which the table contains, are supposed to 
 be of the middle sort: and also that half the 
 weight is supposed lost in making, which 
 occasions the first multiplying by 2 ; but, as 
 this method is more laborious and intricate, 
 in regard to stones of odd weights, the table 
 will be found of much convenience. 
 
 An instance is here given as a proof of a 
 diamond of seven carats i, in the two dif- 
 ferent methods of valuing. For example, 
 the first method is this : the weight of a stone 
 
DIAMONDS AND PEARLS. 69 
 
 of seven carats J must be doubled, which 
 makes fifteen carats f ; next, that weight 
 must be multiplied by 4 to bring it to grains, 
 that makes 63 ; then multiply 63 by 63, 
 that makes 3969, the square of the weight 
 in sixteenths ; therefore divide the 3969 by 
 16, that brings it again to carats, which 
 makes 248 carats and T v ; which multiplied 
 by 2 pounds, produces 496/. 2s. 6d. The 
 second method is this : first, see what a dia- 
 mond of seven carats % is worth per carat, 
 which will be found to come to 63 pounds ; 
 first, multiply 7 by 63, that makes 441 
 pounds ; then add the value of | of 63 
 pounds, which comes to 55/. 2s. 6d. ; these 
 two sums added together, produce 496/. 2$. 
 6d., so both totals are alike, and agree with 
 the price of one of the above weight in the 
 table. 
 
 It will be here proper to observe farther, 
 that no notice is taken of the additional 
 price, which the expense of manufacture 
 would occasion in each stone. This is omit- 
 ted on account of the different prices their 
 different sizes and weights demand ; and, 
 likewise, on account of the different prices 
 
 G2 
 
70 A TREATISE ON 
 
 which their various substances require. These 
 circumstances render it impracticable to be 
 inserted ; and, therefore, the prices of both 
 are contained in four tables, exhibited at the 
 end of the treatise. The first table contains 
 the price of full-substanced, or full-propor- 
 tioned brilliants, explained as follows : the 
 first column exhibits a supposed increase of 
 size and weight, from a stone of a carat, to 
 one of a hundred carats. The first five ar- 
 ticles are carried on by the increase of one 
 carat each, the following by five carats each. 
 The second column contains the price of 
 their workmanship, according to their in- 
 crease in weight, at the rate of II. per carat. 
 The reason of carrying on the gradation by 
 the increase of five carats, is for the sake of 
 brevity ; as the different prices of the inter- 
 mediate weights are inconsiderable, com- 
 pared with the increased value of such stones. 
 The first table being explained, it will serve 
 as an explanation of the other three. 
 
 The second table exhibits the price of 
 making spread brilliants, which is rated at 
 II. 5s. per carat ; and is so done for the fol- 
 lowing reasons ; namely, that all spread 
 
DIAMONDS AND PEARLS. 71 
 
 stones require more care than full-substanced 
 ones, and are riot so soon despatched. The 
 third and fourth tables regard the price of 
 manufacturing rose diamonds; which manu- 
 facture demanding less labour than that of 
 brilliants, causes the price to be one-fourth 
 less, as will be seen by the third table regard- 
 ing full-substanced, or full-proportioned rose 
 diamonds. The fourth table regards spread 
 rose diamonds, the price of which is the same 
 with that of full-substanced brilliants ; which 
 is so raised for the same reasons as have been 
 given in the case of spread brilliants. 
 
 N.B. The prices in these tables are to be 
 doubled in wrought stones, half the weight 
 being lost in manufacturing. 
 
 If I had not inserted the different expenses 
 of manufacturing diamonds, it would be 
 found wanting in the value of every stone ; 
 but may now be easily supplied from the 
 tables just explained. An instance will fully 
 evince their use, which I will give in the 
 case of a full-proportioned brilliant. For 
 example : suppose the value is required of 
 one of the mean, or middle sort, of 7g ca- 
 rats : the diamond, exclusive of the expense 
 
72 A TREATISE ON 
 
 of workmanship, comes to 4961. 2s. 6d. ; the 
 expense of workmanship must be reckoned 
 at 31. \5s. per carat, which comes to 261. 14s. 
 4%d.; that being added, the whole makes 
 5221. 16s. lOJd. 
 
 From the various helps contained in this 
 book, it may be reasonably expected, that 
 such as are skilful in diamonds, and ac- 
 quainted with the current price of them, 
 will hereafter universally agree. 
 
 The innate perfections and imperfections 
 of diamonds, come next under notice. 
 
 Of the innate Perfections, Imperfections, and 
 Water of Diamonds. 
 
 THE circumstances which distinguish the 
 finest diamonds are these. Their com- 
 plexion must be like that of a drop of 
 the clearest rock water : and if such stones 
 be of a regular form, and be truly made, 
 and free from stains, fouls, spots, specks, 
 flaws, and cross veins, they will carry the 
 
DIAMONDS AND PEARLS. 73 
 
 highest lustre of any whatever, and will be 
 esteemed the most perfect. 
 
 If any are tinctured yellow, blue, green, 
 or red, in a high degree, which seldom hap- 
 pens, they are next in esteem ; but, if any 
 partake of these colours only in a low de- 
 gree, it sinks their value below the before- 
 mentioned. 
 
 There are other complexions of a more 
 compound sort, such as brown, and those of 
 a dark hue. The first of these sometimes 
 resemble the brownest sugar-candy, the lat- 
 ter dusky iron. And if any diamonds are at- 
 tended with stains, fouls, spots, specks, flaws, 
 and cross veins, it will abate their lustre and 
 sink their value. Here it may be observed, 
 that what is commonly called the first water 
 in diamonds, means the greatest purity and 
 perfection of their complexion, which, as 
 was said, must be like a drop of the clearest 
 rock water. When any speak of a diamond 
 falling short, more or less, of that perfection, 
 it is expressed by saying, it is of the second 
 or third water, &c., till a stone may be pro- 
 perly called a coloured one. And to speak 
 of a diamond imperfectly coloured, and con- 
 
74 A TREATISE ON 
 
 taining any other defects, as a stone of a bad 
 water only, is very improper ; as it does not 
 convey any idea of the particular colour or 
 defects belonging to it. 
 
 Of the superior Worth of Diamonds over all 
 other Jewels. 
 
 DIAMONDS have, in every age, been esteem- 
 ed the chief of jewels, on account of their 
 innate specific qualities ; which, if not ex- 
 hibited by proper skill, remain imprisoned. 
 It is certain that, in their natural state, 
 they have not so much beauty or lustre, 
 as some other sorts of jewels ; but when 
 truly and judiciously manufactured, they 
 throw forth a splendour and lustre, sur- 
 passing all others, which justly entitle them 
 to the most perfect workmanship, and will 
 consequently be the most likely means of 
 perpetuating them in the esteem of the 
 world. And this will tend to establish their 
 worth, and secure every one's property there- 
 in ; whereas a neglect of exhibiting and dis- 
 
DIAMONDS AND PEARLS. 75 
 
 playing their beauty, by proper workman- 
 ship, will render them unworthy ornaments 
 of the great and distinguished ; which, of 
 course, must sink their value. These consi- 
 derations, doubtless, will influence the cu- 
 rious and discerning, to give all due counte- 
 nance to their being exhibited, in future 
 times, with that beauty and lustre of which 
 they are susceptible. 
 
 And if the following additional circum- 
 stances be taken notice of, they will farther 
 show, that diamonds deserve the chief regard 
 of all jewels. First, they are the best repo- 
 sitory of wealth ; inasmuch as they will lie 
 in the smallest space of any, and are there- 
 by the most portable and best conveyance 
 of treasure. Next, their superlative hard- 
 ness secures them from all injury by wear ; 
 as nothing can make any impression on 
 them, or prejudice their lustre, but their 
 rubbing against each other. They can only 
 be affected by fire, and that must be strong 
 and lasting to do them much harm ; and the 
 injury they receive thereby, arises chiefly 
 from taking them too hastily from thence, 
 whereby the immediate impression of the 
 
A TREATISE ON 
 
 cold air may possibly produce flaws, &c. A 
 moderate fire will only occasion a roughness 
 on their surface, which may be repaired by 
 new polishing. 
 
 Reasons for working Diamonds in a complete 
 Manner, and the Consequences resulting from 
 a contrary Practice. 
 
 WHAT has been said of the superlative 
 properties of diamonds, &c., seems sufficient 
 to recommend them to the protection of 
 mankind, from any abuse arising by ill 
 workmanship, as their pleasure, honour, and 
 interest, are concerned in it; and nothing 
 appears wanting to influence thereto, but 
 that of the world being convinced of the 
 
 o 
 
 necessity of it, from being made acquainted 
 with the abuse that diamonds have sustained 
 by the contrary practice. To that end I 
 shall first resume the observation that has 
 been made on small brilliants ; which is, 
 that they are in general so ill wrought, as to 
 be void of their true beauty and lustre, and 
 
DIAMONDS AND PEARLS. 77 
 
 will not fill up, by one-fourth or one-third, 
 the space that well-wrought stones do, in a 
 piece of jewelling work ; of course, pur- 
 chasers of such are deprived of one-fourth or 
 one-third of the show or appearance that 
 well-wrought stones would make, and of 
 the beauty and lustre that always accompany 
 such ; next, that the same effects attend 
 stones of larger sizes, made after the same 
 manner. 
 
 N. B. The same ill effects also attend small 
 or large rose diamonds, made in the same 
 manner. 
 
 The ends and purposes that are to be 
 served by this manner of working, naturally 
 fall under consideration : the most that can 
 be pretended, is, that by the world being 
 brought into a favourable notion of these 
 goods, on account of buying them at a lower 
 price by weight than well-wrought stones, 
 trade has been increased, and more hands 
 employed ; but it cannot mean the increase 
 of England's trade, for that has been declin- 
 ing many years, and its hands unemployed, 
 to the great impoverishment of the whole 
 body of workmen, and those known to be 
 H 
 
78 A TREATISE ON 
 
 as good as any, if not the best, in the world; 
 and which has arisen from their refusing to 
 work after this rude manner, and not being 
 able to support themselves by the wages that 
 are given abroad for such work, which ap- 
 pears not equivalent to the wages here given 
 to the meanest handicraftsmen. 
 
 Admitting our neighbours have increased 
 the traffic, and employed more hands of the 
 lowest sorts than we could ever boast of, let 
 the consequences which are like to flow from 
 this manner of working be considered. 
 
 By the continuance thereof, the clisesteem 
 that has of late been shown to diamonds 
 may increase ; which principally has taken 
 its rise from thence, particularly in England : 
 and that, probably, has been forwarded by 
 the good appearance which crystal or false 
 stone- work, commonly so called, has made of 
 late Con which all the embellishment that 
 care and skill can procure, has been bestow- 
 ed). This is observed to the credit and re- 
 putation of these traders and their work- 
 men ; and, in consequence thereof, this com- 
 modity frequently passes for diamonds : and 
 if the same care should be taken in com- 
 
DIAMONDS AND PEARLS. 79 
 
 pleting that sort of work for foreign use, 
 they also may enter into the like contempt of 
 diamonds ; if so, what will become of this 
 boasted increase of trade ? But if the truth 
 of the diamond manufacture be supported, 
 their lustre will conspicuously excel the faint 
 and languid efforts of all crystalline matter, 
 with all the helps of art. 
 
 To disgrace this first-rate gem by ill work- 
 manship, in bringing it down almost to the 
 level of this commodity, seems to be very un- 
 warrantable ; especially as it tends to sink 
 this part of public wealth, and is a manifest 
 discouragement to art and ingenuity ; and 
 also of great prejudice to fair traders, who 
 scorn to submit to the encouragement of such 
 mean, deceitful artifices, to enrich themselves. 
 
 But, notwithstanding what has been offer- 
 ed, to show the impropriety and ill-conse- 
 quences of working diamonds in an ill man- 
 ner, it is to be feared, that such as have hi- 
 therto found their account in it, will pursue 
 the same method, so long as they can find it 
 their interest so to do. To prevent this 
 abuse, the sizes of brilliant and rose dia- 
 monds are exhibited, by which any one may 
 
80 A TREATISE ON 
 
 know, whether a diamond of either manu- 
 facture be well or ill made ; and this is 
 thought the most effectual means of putting 
 a stop to it; judging all persons, who have 
 any considerable value of this kind, will af- 
 ford their assistance in discountenancing such 
 an injurious practice ; if so, the world will 
 see persons of rank and fortune distinguished 
 from others, by the inimitable lustre of these 
 jewels ; for which purpose, doubtless, they 
 were intended. 
 
 But it may be said, that many persons of 
 rank and fortune are possessed of such ill- 
 wrought stones ; and the encouraging of 
 this refinement of manufacture will make 
 them appear in a worse light. This is al- 
 lowed ; but, at the same time, it is to be 
 understood, that all ill-wrought stones are 
 capable of being made as perfect, in respect 
 to workmanship, as any, without the least 
 loss of their expansion or breadth ; and that 
 such rectified stones will appear to sight ra- 
 ther larger than their present form ; for 
 by being made more open, every part of 
 their upper surface will be more clearly seen, 
 and what loss of weight they sustain will 
 
DIAMONDS AND PEARLS. 81 
 
 be compensated by the remaining weight 
 being of more value ; or, in other words, 
 that weight will be worth more per carat ; 
 and then such will weigh as much as they 
 ought when sold ; and by this means indif- 
 ferent diamonds may be made fine, if the 
 matter or stuff be such, which is frequently 
 the case ; and the reason of their being but 
 indifferent before, was their being over- 
 loaded with weight, and otherways ill- 
 wrought, which obscured their true lustre. 
 This compliance with what is proposed, 
 will make them of rather more value than 
 when bought; and the loss to the purchaser 
 is that which is paid for rectifying them. 
 This will prove a greater disadvantage to 
 the purchasers of small diamonds, than to 
 the purchasers of larger stones, as the work- 
 manship of small stones is a considerable 
 part of their value. 
 
 Here it may be proper to observe, that 
 the worst workmanship is frequently per- 
 formed on coloured stones, to render them 
 cheap, by which means they are generally 
 despised ; instead of that, they should have 
 all the advantage that art can bestow on 
 
 H2 
 
82 A TREATISE ON 
 
 them, to recommend them to the just favour 
 of the world. And stones, however co- 
 loured, that are not attended with specks, 
 spots, fouls, stains, or any other defects, to 
 weaken their lustre, ought to have the utmost 
 skill of workmanship ; and numbers there 
 are, if well-wrought, that would carry as 
 much or more vigour and spirit, than many 
 that do not fall under that denomination ; 
 and, therefore, if any made stones appear 
 susceptible of an improvement of their lus- 
 tre, by being rectified, it is fit that such 
 should receive the benefit thereof; for the 
 sake of the pleasure and credit it must af- 
 ford the owners, and the reputation that 
 such a conduct will bring to this species of 
 jewels. And it is to be imagined, that this 
 will be thought worthy of some notice, as 
 the world seems so strongly disposed to 
 value perfection in this jewel ; and none can 
 be said to be so, that has any manifest imper- 
 fection of workmanship. 
 
 And here I shall take the liberty to ob- 
 serve, that the truth of the manufacture of 
 either was never brought under any stated 
 rules of practice ; nor was there any recourse 
 
DIAMONDS AND PEARLS. 83 
 
 to be had to prove the truth of the manu- 
 facture of any diamond, till this treatise 
 made its first appearance ; and for want of 
 something of this kind, there have been, in 
 all times past, innumerable disputes amongst 
 workmen, concerning the true method of 
 working diamonds. 
 
 But this must be owned, that the fewest 
 disputes on this head, have been found 
 amongst those of the best judgment; and, 
 moreover, it is known that their practice, 
 when left to work agreeably to their own 
 sentiments, has nearly been conformable to 
 the rules here advanced ; and to which 
 practice they would always have adhered, if 
 left at liberty ; but the selfish views of those 
 they have wrought for have obstructed it, 
 and laid them under a necessity of work- 
 ing according to the directions given them. 
 This has been the cause of so much defective 
 workmanship on diamonds, and not only on 
 middling stones, but likewise capital ones. 
 
 This was the very cause of the largest 
 diamond, that ever appeared in Europe, 
 being wrought in a deficient manner ; which, 
 if it be now as it came out of the hands of 
 
84 A TREATISE ON 
 
 those who wrought it, I take the liberty to 
 say, may be rendered complete ; by which 
 means its form will be more comely and 
 graceful, its lustre greatly increased, and of 
 course its value, although its weight may 
 be something reduced ; and then it may be 
 said to possess all the dignity that nature has 
 favoured it with, and likewise that art has 
 done it justice. 
 
 The first fact I can make appear, by two 
 leads cast from the stone ; one when it was 
 a rough diamond, the other when cut and 
 polished ; and the second, how it came to 
 be wrought as it was, I can prove by incon- 
 testable evidence, &c. 
 
 That this is the case of this and many 
 other large diamonds, is not to be wondered 
 at ; but rather how those, who had the di- 
 rection of manufacturing such stones, were 
 influenced to submit to the loss of so much 
 weight, having nothing but conjecture to 
 direct their conduct ; and their having left 
 an over-weight, must be owned to be an er- 
 ror of the right side, as that may be dis- 
 charged, whenever it is thought proper ; 
 and it can scarcely be imagined, that any 
 
DIAMONDS AND PEARLS. 85 
 
 will be fond of retaining weight irr a stone, 
 that renders it ungraceful in its figure, and 
 destroys its life and vigour ; especially as its 
 expansion is not lessened thereby, but will 
 appear to sight larger than before; which, 
 perhaps, may cause a stone to be deemed 
 good, that before was ranked in a lower 
 class. And, as it has been before said, such 
 stones will be worth as much or more, not- 
 withstanding the reduction of their weight, 
 than when possessed of their former weight, 
 by the remaining weight being of a higher 
 worth ; so the expense of rectifying them 
 is the only loss that will be sustained. 
 
 The Use of the Sizes in purchasing Rough 
 Diamonds. 
 
 As the use of the sizes cannot but be suf- 
 ficiently seen in regard to wrought stones, 
 they will appear of equal use in regard 
 to rough diamonds ; inasmuch as they will 
 assist the judgment, concerning the loss 
 of weight that may be sustained in working 
 
86 A TREATISE ON 
 
 any diamond ; and therefore must be of great 
 service towards forming a right notion of 
 their value, as it is well known that some 
 rough diamonds must sustain a much greater 
 loss or diminution of weight than others, 
 arising from their peculiar shapes. And to 
 form a true judgment of the value of any 
 rough diamond, the price or value of one of 
 a carat weight, similar to the stone which is 
 to be purchased, determines its value, as in 
 the case of manufactured diamonds. But as 
 it is more difficult to judge what a rough 
 diamond will prove when cut, than to judge 
 of one manufactured, the buyer, supposing 
 him a merchant, must act with proper pre- 
 caution, and make sufficient allowance to 
 himself, for the uncertainty of the stone 
 answering expectation when wrought. And, 
 if it be a stone of a considerable value, he 
 must allow himself also for the interest of 
 the money he lays out, according to the time 
 he supposes the stone may remain unsold. 
 These precautions are the only means of 
 guarding against the hazards and disadvan- 
 tages that attend dealing in large rough 
 diamonds ; and, by such a conduct, dealers 
 
DIAMONDS AND PEARLS. 87 
 
 may be enabled to sell at a price, agreeable 
 to the estimation of the skilful ; which esti- 
 mation is the only thing to be regarded, by 
 those who purchase them for their own use. 
 To urge any other considerations to the pur- 
 chaser, for augmenting the price of any 
 diamond beyond its just value, will, it is 
 humbly apprehended, be judged a weak- 
 ness, and likely to hinder the sale of such 
 goods. 
 
 But, if it should be here remarked, that 
 particular cases or occasions may justify the 
 seller in demanding an advanced price for 
 any diamond, such deviations must be con- 
 sidered as merely occasional, and the buyer 
 is at liberty whether he will comply or not. 
 
 Remarks on the India Manufacture of Dia- 
 monds, and their Custom in Regard to Rough 
 Diamonds. 
 
 ALTHOUGH it has been supposed, under 
 the head of valuing diamonds, that the 
 India people are acquainted with the prin- 
 
88 A TREATISE ON 
 
 ciple of estimating them, it will be now 
 shown, that they are masters of no other 
 essential parts of knowledge concerning 
 diamonds. 
 
 The manufacture of them they seem to 
 know very little of, as appears by the wrought 
 stones that come from thence, none of them 
 being fit for use, and therefore are always 
 new wrought when brought to Europe, 
 which I shall describe as follows : they are 
 called lasks ; they are in general ill-shaped, 
 or irregular in their form at the girdle ; their 
 substance or depth is ill-proportioned ; some 
 have more of the stone's substance at top 
 than at the bottom ; their tables are seldom 
 in the middle or centre of the stone, and 
 the collets the same; and sometimes the 
 tables are of an extravagant breadth, and 
 sometimes too small ; in the same manner 
 are their collets, and seldom horizontal ; and 
 their girdles are often very thick and not 
 level ; the small work very irregularly per- 
 formed, and none are properly polished ; 
 and the chief thing regarded, is that of sav- 
 ing the size and weight of stones : and this 
 is not much to be wondered at in them, as 
 
DIAMONDS AND PEARLS. 89 
 
 they are unacquainted with the beauties of 
 well-wrought diamonds. From hence it 
 will appear, that they must be unqualified 
 to judge of the true worth of individual 
 rough diamonds. For instance: they can- 
 not know what a diamond will lose in work- 
 ing, to be well made ; nor can they know, 
 if a stone be coloured, what degree of co- 
 lour it will retain, or what life and spirit a 
 stone will carry well wrought ; all which 
 they are very conscious of; and this makes 
 it very difficult to trade with them for single 
 stones. 
 
 But it is not so difficult to trade with them 
 for parcels, because in them there are stones 
 of all shapes; and as some will lose more, 
 some less, they guess at that as well as they 
 can; and so in respect to their other pro- 
 perties, in which they are not quite so much 
 at a loss ; and then they value them by the 
 lump, as they weigh one with another, by 
 the rule. 
 
 From whence we may see, how necessary 
 it is for Europeans to be furnished with 
 knowledge, as by that means they must 
 have some advantageous opportunities in 
 
90 A TREATISE ON 
 
 buying large stones, through the ignorance 
 of these people. Although it has been 
 shown how much regard they have to the 
 saving of weight in working of diamonds, 
 their attachment thereto will further appear, 
 by the following custom having prevailed 
 time out of mind, the reality of which seems 
 not be doubted. 
 
 The great people there employ a vast 
 number of slaves in search of diamonds ; the 
 small and middle size diamonds they sell, 
 and some of the large ones ; but when they 
 are fortunate in meeting with a very large 
 one, they lay it up as a treasure, to aggran- 
 dize their family ; and the head of the fa- 
 mily has a small shallow hole drilled on the 
 surface of the stone, and when he dies, the 
 next chief does the same, and so from one 
 to another : and the more of these holes a 
 stone has, the higher it is in esteem, although 
 such holes may prejudice it, if it were to be 
 manufactured ; but as that is never intended, 
 they do not regard such prejudice ; and these 
 stones are never parted with, let what will 
 happen ; and if they foresee any ruin to the 
 family (as that sometimes happens in their 
 
DIAMONDS AND PEARLS. 91 
 
 further pursuit of diamonds, which is very 
 expensive by the vast number of hands they 
 employ in that undertaking), in such cases 
 they bury those stones, so that they never 
 appear again. For they cannot bear the 
 thought of any others having the possession 
 of that which they have obtained at so great 
 an expense; and it is said, that, in conse- 
 quence of that custom, there are many very 
 large diamonds irrecoverably lost, and like- 
 wise many that will never be parted with. 
 
 This custom is imagined to arise from 
 their being fearful of a diamond's losing its 
 value, by losing weight and magnitude in 
 being wrought ; which is very true, as they 
 work them, because they are void of lustre ; 
 and therefore it is not an unreasonable con- 
 duct in them, on that account alone ; but 
 there is another reason assigned for it, which 
 is, the hazard their diamonds are exposed to 
 by their manner of working : this is much 
 greater than what attends the working of 
 diamonds in Europe, for they perform it in 
 a rougher manner than is done by the Eu- 
 ropeans, more especially in respect to polish- 
 ing them ; in doing of which they lay an ex- 
 
92 A TREATISE ON 
 
 cessive weight on their diamonds through 
 unskilfulness (and for want of such curious 
 machinery or mills, as are in Europe), which 
 makes it not practicable for them to give 
 diamonds a true polish. 
 
 N. B. Although this is the case in respect 
 to the India manner of working, there come 
 now and then stones tolerably well wrought 
 and polished ; but these have been supposed 
 to have been done by Europeans, and upon 
 their mills and skeves, and to have been the 
 property of such. 
 
 Some Account of Authors, who have heretofore 
 treated of Diamonds and Pearls, and the Im- 
 provements which have been made since their 
 Times. 
 
 THOUGH what I have advanced is really 
 the produce of many years' critical observa- 
 tion, in the course of dealing in rough 
 and polished diamonds, and has been a 
 work of much time, labour, and great ex- 
 pense ; I am not a little pleased to see it 
 
DIAMONDS AND PEARLS. 93 
 
 agree with what I have since found to be 
 mentioned by some celebrated writers, who 
 have exhibited the principle upon which 
 diamonds are to be valued. The first which 
 fell into my hands was Monsieur Tavernier, 
 who mentions it in his voyages through Tur- 
 key, Persia, and the East Indies ; which he 
 published in the year 1670, and which were 
 translated into English in the year 1678. 
 The next was the memorable Mr. Lewis 
 Roberts, who published it in his Map of 
 Commerce, in the year 1638. Sometime 
 after, I communicated the principle of va- 
 luation I have exhibited in this treatise to 
 an acquaintance of mine, who was a dealer 
 and a diamond-cutter, and who had lived 
 many years at Fort St. George in that capa- 
 city > by whom I was informed, that the In- 
 dia traders (meaning the natives of India) 
 had some established rule of estimating dia- 
 monds, &c., which he believed to be the 
 same with what I then proposed. At length, 
 several years after the perusal of the above 
 writers, a still more ancient one was shown 
 me by means of a gentleman of. great learn- 
 ing, and of great figure in the literary world, 
 i 2 
 
94 A TREATISE ON 
 
 This author was John Arphe de Villa Fane, 
 who speaks of the principle of valuation in 
 his treatise, entitled " The Standard of Gold, 
 Silver, and Precious Stones," published in 
 Spanish in the year 1572, by the King of 
 Spain's especial licence. These writers have 
 mentioned some attempts to settle rules for 
 the manufacture of diamonds ; but, it is to be 
 observed, that not only what they have de- 
 livered is very imperfect, but that when they 
 wrote, the art of making brilliants was not 
 discovered; which manufacture is essential 
 to the saving of the weight formerly lost, by 
 cutting all rough diamonds into tables and 
 roses ; to prevent which loss of weight, as 
 much as possible, a heavy load of sub- 
 stance has been left on both these kinds of 
 manufacture. Moreover, to save weight, 
 rough diamonds have been frequently sawed, 
 especially such as had no corners, in order 
 to make them into roses ; but this practice 
 was attended with a much greater ex- 
 pense of workmanship, and withal, a much 
 greater loss of weight, than they have 
 been subject to, since the making of bril- 
 liants has been introduced ; this latter ma- 
 
DIAMONDS AND PEARLS. 95 
 
 nufacture being more suitable to stones of 
 most shapes. 
 
 These observations show, that if the truth 
 of the manufacture of table and rose dia- 
 monds had been known in times past, which 
 appears not to have been the case, although 
 it might have been of use in preventing the 
 past defective manner of making them, it 
 could not procure the advantages which 
 flow from the addition of the brilliant manu- 
 facture, since that renders the whole a com- 
 plete system ; and not only contributes to 
 the greatest saving of weight, but likewise 
 ascertains the general loss of weight, as has 
 been already observed, which could not be 
 known till the manufacture was reduced to 
 settled rules. The want of this, probably, 
 occasioned a disregard of what has been 
 taken notice of by these authors, concerning 
 the manufacture and valuation of diamonds. 
 The next thing to be considered is pearls. 
 
96 A TREATISE ON 
 
 Of Pearls, their Perfections and Imperfections. 
 
 THESE jewels are next in importance to 
 diamonds, as they constitute the next great- 
 est share of wealth of any other kind. 
 The first thing to be observed concerning 
 them, is, that what beauty they possess, 
 is the mere produce of nature ; and that 
 they are not susceptible of any advantages 
 or helps by art ; a circumstance which re- 
 commends them to the esteem of the world. 
 Those of the finest shape are perfectly round, 
 which fits them for necklaces, bracelets, 
 jewels for the hair, and other such like 
 uses. But if a pearl, of any considerable 
 size, be of the shape of a pear, it is not 
 reckoned an imperfection; because it may 
 be suitable for drops to ear-rings, solitairs, 
 and many other jewels. Their complexion 
 must be milk-white, not of a dead and life- 
 less, but of a clear and lively hue, free from 
 stains, fouls, spots, specks, or roughness; 
 such are of the highest esteem and value. 
 
 Pearls are defective when rough, spotted, 
 or dull ; whether that be owing to any mis- 
 
DIAMONDS AND PEARLS. 97 
 
 carriage of nature, or to age, to wear, or any 
 other accident ; when irregular in their 
 shapes, be they flat or hollow, craggy or 
 gibbous ; when they are stained with any co- 
 lour, as yellow, blue, green, red, brown, or 
 that of a dusky iron. It is also an imperfec- 
 tion when they have large drilled holes, or 
 are rubbed flat about the edges of the holes 
 by long use. These defects cause a yery 
 considerable difference in the value of pearls, 
 of the same weight and size. 
 
 Of the Rule of valuing Pearls. 
 
 THE only rule of valuing them, is by the 
 square of their weight, as in the case of 
 diamonds ; nature producing them after the 
 same manner, viz. a vast number of small 
 ones, and progressively a less number of 
 larger, as they increase in size and weight. 
 Upon this principle two tables are formed, 
 of the prices of pearls. The first eight con- 
 tain those of a carat weight downwards, of 
 eight different values, which will be found in 
 
98 A TREATISE ChV 
 
 plates XVII, XVIII, XIX, XX, XXI, XXII, 
 XXIII, XXIV. The first being explained, 
 it serves for the other seven. The first co- 
 lumn contains the number of pearls in an 
 ounce troy, from those of a carat weight to 
 such as weigh but the 32nd part of a carat. 
 The second column contains the progressive 
 decrease of their weight, from those of one 
 carat, to those of the 32nd part of a carat. 
 The third contains their several prices, from 
 one carat at 2s. to those of the ^ part of a 
 penny. The fourth contains the price of an 
 ounce, at the rate of 2s. per carat, which 
 makes 15/., to that of the smallest size, which 
 is 9*. 4jd. 
 
 The next thing to be taken notice of, is a 
 table that relates to pearls, of a carat weight 
 and upwards, to a hundred carats, which 
 will be found in plates XXV, XXVI, 
 XXVII, XXVIII, XXIX, XXX. The prices 
 of pearls in this table are founded upon the 
 supposition, that the general price of pearls, 
 good and bad blended together, is Ss. per 
 carat ; which will be found to be the first 
 article in it. This table, therefore, will be of 
 the same use with regard to pearls, as the 
 
DIAMONDS AND PEARLS. 99 
 
 diamond table is in regard to diamonds. 
 For, if any pearl exceeds in quality, or falls 
 short of, those of the middle sort, the rise 
 or fall, upon the price of a pearl of any 
 weight, must be so much per cent, as judg- 
 ment shall direct; which prevents all trouble 
 of finding it out by the rule. To show the 
 convenience of this table, the following ex- 
 ample may be given. If the value of a pearl 
 of 4 carats f is required, which may be sup- 
 posed to be 10 per cent, better than one of 
 the mean or middle price, its price will be 
 found, by the table, to be 91. 10*. Ijrf. 
 Then 19*. is to be added, which is the pro- 
 duce of the 10 per cent, and makes its value 
 to be 10/. 9*. 1W. 
 
 To find out the first price by the rule, re- 
 duce the 4 carats f into eighths, which 
 makes 39; then multiply 39 by 39, that 
 makes 1521, the square of the weight in six- 
 teenths; therefore divide 1521 by 16, that 
 brings it again into grains, and makes 95 ; 
 then divide the 95 by 4, that brings it to 
 carats, and makes 23 carats, 3 grains, and 
 & of a grain ; which, at Ss. per carat, pro- 
 duces 91. 10*. \\d. 
 
100 A TREATISE ON 
 
 And as another method is introduced for 
 rinding out the value of diamonds, which is 
 as applicable to pearls, the foregoing weight 
 is made use of as an example. 
 
 For instance : see what a pearl of 4 carats 
 comes to at Ss. per carat, which will be 
 found to be 39s. ; so multiply 39 by 4, that 
 makes 156s. , or 71. 16s. ; then add the value 
 of f of 39s., which is I/. 14s. \\d. ; cast up 
 the two sums, and that will produce 91. 10s. 
 l\d. : so these two totals are alike, and 
 agree in price with one of that weight in the 
 table ; and that being the price of one of 
 the middle sort, the value of the 10 per cent, 
 must be added, which is 19s. ; so the value of 
 such a pearl is 10/. 9s. 1 \d. 
 
 These instances are supposed sufficient to 
 show, how much readier the value of any 
 single pearl is to be found, by making use of 
 the table ; the usefulness of which will ap- 
 pear in a stronger light, when it is considered 
 what number of occasions pearls furnish by 
 their multiplicity, and likewise the small 
 value they are of individually, although not 
 so regarding their quantity. 
 
DIAMONDS AND PEARLS. 101 
 
 N. B. Their value, compared with dia- 
 monds, is but as 8s. to 8/. 
 
 As an application to the table appears to 
 be by far the readiest way of coming at the 
 value of any single pearl, its farther useful- 
 ness will be shown in valuing any parcels of 
 pearls. 
 
 For instance : suppose a parcel of pearls 
 (be their number and weight what they may) 
 and various in respect to their qualities or 
 goodness ; first, weigh the parcel altogether ; 
 when the weight is known, count their 
 number ; when that is known, see what the 
 weight would be per piece, if they were all of 
 one weight, and then endeavour to form a 
 judgment what they may be rated at per carat, 
 as a mixed parcel : having settled that, see 
 what a pearl is worth, of the weight you 
 found they would be of if they were all of 
 equal weight or size, and then value the 
 weight of the whole parcel by the price ot 
 that pearl, and that will give the value of the 
 whole parcel. To illustrate this, suppose 9 
 pearls of 9 several weights, which may be of 
 different qualities or goodness, but being- 
 blended together they may be reckoned worth 
 
 K 
 
102 
 
 A TREATISE ON 
 
 8s. per carat. As this supposed price agrees 
 with the table, the example will be drawn 
 from thence, and will begin with the first 
 article therein, as underneath : 
 
 1st - 
 
 2nd - 
 
 3rd - 
 
 4th - 
 
 5th - 
 
 6th - 
 
 7th - 
 
 8th - 
 
 9th - 
 
 - of 
 
 Carats. 
 
 1000 
 } 
 J 
 
 1 I 
 J 
 
 1 i 
 i i 
 \ I i 
 
 2000 - - 
 
 s. d. 
 080 
 
 10 1J 
 
 12 6 
 
 15 1J 
 
 18 
 
 1 1 1} 
 1 4 6 
 
 1 8 1J 
 
 1 12 
 
 The 9 weigh - 13J and come to 896 
 
 The above 9 pearls weighing 13 carats |, 
 would make the weight of each 1 carat J, the 
 price of which in the table is 18s. therefore 
 multiply 18$. by 9, the number of the pearls, 
 that makes 162s. or SI. '2s. 
 
 The value, rating them by their several 
 weights, as above, makes the total 8/. 9s. 6d. 
 which is 7s. 6d. more than by the other me- 
 thod of valuing them ; and this arises from 
 
DIAMONDS AND PEARLS. 
 
 103 
 
 the loss of fractions in that case ; and al- 
 though that be something in this sum, it is 
 not worth regard in a larger sum, which will 
 be the same when pearls are rated at Ss. per 
 carat ; and for farther satisfaction the fol low- 
 ing- case is inserted. 
 
 1st - - - of 
 
 2nd - - - 
 
 3rd - - - 
 
 4th - - - 
 
 oth - - - 
 
 6th - - - 
 
 7th - - - 
 
 8th - - - 
 
 9th - - - 
 
 The 9 weigh - 
 
 Carats. 
 6000- 
 
 6 i - 
 
 6 J - 
 
 6 J i - 
 
 6 J - 
 
 6 J J - 
 
 6 J i - 
 
 7000- 
 58i 
 
 s. d. 
 
 14 8 
 
 15 1J 
 
 15 12 6 
 
 16 5 1| 
 
 16 18 
 
 17 11 1J 
 
 18 4 6 
 
 18 18 1J 
 
 19 9 6 
 
 152 9 6 
 
 The above 9 pearls weighing 58 carats J, 
 would make the weight of each 6 carat J, the 
 price of which in the table is 16/. 18$. 
 First, multiply 9 by 16/. that makes 144/. ; 
 next, multiply 9 by 18*. that makes 8/. 2y., 
 add these two sums together, the total will 
 be 152/. 2s. which is Is. 6d. short of the 
 
104 A TREATISE ON 
 
 above sum of 152/. 9s. 6d. But if the num- 
 ber of articles had been more, and the price 
 of any parcel of pearl should be higher, it 
 can but little increase the difference ; and 
 therefore it is not worth regarding, more es- 
 pecially when it is considered, that none can 
 judge the value of any one pearl, or parcel, 
 to any such-like nicety. As to what has 
 been said of the convenience of this table, 
 the same might have been said of the dia- 
 mond table ; but as there seemed not to 
 be the like necessity for it, in regard to dia- 
 monds, it has hitherto been omitted, and the 
 rather, to avoid repetition. 
 
 As the convenience of this table is evi- 
 dently shown, it may be proper to observe, 
 that in making- use of that, or either of the 
 other methods for finding the value of pearl, 
 the highest price of any pearl of a carat 
 weight cannot be valued at more than 16s., 
 when the price of the middle sort, of that 
 weight, is valued at 8s. 9 nor those of the 
 lower sort, of a carat, at less than 2s. ; be- 
 cause all of a baser sort deserve not to be 
 considered as jewels. And this, probably, 
 will be thought scope enough to employ 
 
DIAMONDS AND PEARLS. 105 
 
 speculation and judgment; notwithstanding 
 which, it is to be supposed, that all who 
 are skilful will agree in sentiments concern- 
 ing the value of any pearl of a carat weight, 
 however circumstanced, as nearly as in the 
 case of diamonds, as the value of pearls of 
 any weight is to be determined by the price 
 of one of a carat weight, similar in all circum- 
 stances. Or, as was said of diamonds, the 
 same may be said of pearls, that every pearl 
 is to be valued as it is worth per carat, by 
 the rule of estimating. 
 
 N. B. It is to be observed, that what is 
 supposed of judicious jewellers agreeing in 
 their sentiments to five or ten per cent, con- 
 cerning the value of any diamond or pearl 
 of one carat weight, by which the value of a 
 diamond or pearl of any weight is to be de- 
 termined, is to be understood to relate to the 
 natural and just value of them only; and 
 when there is a compliance with any other 
 price, that must be considered as the occa- 
 sional price ; and if persons who buy for their 
 use could be assured what is the just price 
 of any jewel, it would be the means of in- 
 fluencing them to give the value of them. 
 
 K2 
 
106 A TREATISE ON 
 
 And this must necessarily facilitate the trans- 
 actions of this business ; and, I am humbly 
 of opinion, if this had been the case in times 
 past, many capital jewels, which have lain 
 many years in the hands of persons who 
 bought them in order to make profit of the 
 money laid out, would have found pur- 
 chasers of them long ago, to the advantage 
 of their present owners. 
 
 As so much depends on traders being 
 masters of the most complete knowledge of 
 this business, it must be supposed they will 
 not be wanting in improving themselves 
 therein by all means that may be procured, 
 as it will render them a beneficial body to 
 the rest of mankind, and of course raise their 
 characters, which have heretofore lain under 
 disagreeable imputations. 
 
 Here it may be proper to observe, that 
 whatever knowledge persons may have of 
 the just value of jewels, it will not exempt 
 those who buy them for their own use from 
 sustaining a loss in purchasing them ; but it 
 will lessen the losses that might otherwise 
 happen, which the world has heretofore been 
 subject to for want of such knowledge. 
 
DIAMONDS AND PEARLS. 107 
 
 That losses must be sustained is unquestion- 
 able, and that these must vary as circum- 
 stances differ, the following cases will evince. 
 
 Observations on the Losses supposed to be sustained 
 by the Purchase of Jewels. 
 
 THE expence of making some pieces of 
 jewelling work comes to a considerable 
 part of the purchase money ; and gene- 
 rally where there is the least value of dia- 
 monds, the expence is the greatest, as when 
 a large number of small diamonds are em- 
 ployed : when such a jewel is resold, that 
 expence must be deducted, if it be injured 
 by wear or by accident, or it becomes un- 
 fashionable. 
 
 Again, jewellers must be supposed to have 
 a considerable sum of money employed in 
 trade, the returns of which are not very 
 frequent ; and, therefore, a loss must una- 
 voidably attend the purchasing jewels, and 
 the greatest in buying large diamonds, al- 
 though the expence of setting them be less, 
 
108 A TREATISE OX 
 
 on account of their lying much longer in the 
 possession of jewellers than those of the 
 smaller sort ; and therefore all jewellers sup- 
 posing the probability of this, never give so 
 near the value of them as for smaller stones, 
 they being always more marketable. 
 
 As this is the case, persons of rank and 
 fortune, that need not regard any reasonable 
 loss, or the interest of money, are the pro- 
 per purchasers of jewels ; and the money 
 laid out by such persons, can no more be 
 deemed luxury in them, than that which is 
 expended in equipping and furnishing side- 
 boards and cabinets, and on all other costly 
 personal equipments in gold and silver. But 
 it may be said, that the latter are more useful 
 and necessary than the former. To which it 
 may be answered, that their uses may be 
 supplied at a much cheaper rate ; so the ap- 
 pearance and credit must be the remaining 
 motive for laying out money that way, which 
 is the same in respect to jewels ; and if the 
 losses attending the purchasing these be an 
 objection, it will be found to lie as strong 
 against the other, in respect to fashionable 
 elegant things; the workmanship of which, 
 
DIAMONDS AND PEARLS. 109 
 
 upon an average, comes to at least J, if not 
 i, of the purchase money. 
 
 The loss by jewels, it is humbly appre- 
 hended, will not, in future times, exceed 
 that, although it has been otherwise in times 
 past, as appears by instances that have been 
 given ; which show that not above J or J of 
 the purchase money could be obtained for 
 jewels, either by way of pledge or sale ; 
 which has chiefly arose from jewellers not 
 being well acquainted with the natural and 
 just value of them, which cannot be the 
 case in future time; it being evident that 
 traders have it in their power to come at 
 their true value, by estimating them as they 
 are worth per carat, by the rule exhibited. 
 This being the case, any one else may at- 
 tain the knowledge of the value of any dia- 
 mond or pearl, or parcels thereof, by ap- 
 plying to a skilful jeweller, to know what 
 they may be worth per carat. 
 
 And this will be the means of preventing 
 any persons selling their jewels on such dis- 
 advantageous terms, as have been before 
 taken notice of; since they will rather pledge 
 them, and wait for a more favourable offer ; 
 
110 A TREATISE ON 
 
 and a better knowledge of their value will 
 procure more money lent on them, if occa- 
 sion requires it, than in times past. And as 
 the skill of traders appears so useful, they 
 must be supposed to be intitled to a suitable 
 reward, for giving their opinions in all such 
 cases. These measures will tend to support 
 the worth of jewels, and render all property 
 of this kind permanent wealth, exclusive 
 of the deductions a little before mentioned, 
 and make them the proper possession of 
 persons of rank and fortune here, as well as 
 in other countries ; especially if the wealth 
 of the nation increases ; because all pur- 
 chases of income must advance as that aug- 
 ments, and of course brings down the value 
 of money. 
 
 For example : if any one should be forced 
 to give three hundred pounds for an income 
 that in time past could be purchased for two 
 hundred pounds, it is evident that then three 
 hundred pounds is reduced to the value of 
 two hundred. If this be an evil, the laying 
 out the exuberance of our money in jewels 
 seems to be the properest redress of it, as 
 they are a durable, though not a profitable, 
 
DIAMONDS AND PEARLS. Ill 
 
 treasure ; inasmuch as they may be found of 
 convenience in any time of distress, whether 
 private or public. The latter, indeed, we 
 have the happiness to have no reason to 
 fear. 
 
 What has been observed of the utility of 
 jewels, diamonds especially, to persons of 
 dignity, and those of affluent fortunes; and 
 of the conduct of the India people, in not 
 forcing the sale of them, by lowering their 
 price ; but, on the contrary, withdrawing 
 them, when there appears a slack demand, 
 which is supposed to arise from the great 
 expence they are at in the search of them ; 
 for although the price of labour in India is 
 excessively cheap ; yet the hands that are 
 employed in this work, as Monsieur Taver- 
 nier arid other authors have taken notice of, 
 are so very numerous, that it makes it a 
 costly, and even a precarious undertaking ; 
 and considering that, notwithstanding Eu- 
 rope has been supplied with diamonds from 
 thence, and from the Brazils, within twenty 
 years last past, abundantly more than in any 
 preceding number of years; yet the amount 
 of the annual value of them, on an average, 
 
112 A TREATISE ON 
 
 comes a great deal short of two hundred 
 thousand pounds sterling : and farther con- 
 sidering, that many countries are come more 
 into the use of them, of late years, than for- 
 merly; and that some, which in times past, 
 were almost strangers to their existence, are 
 now buyers of them, but principally the 
 most indifferent sort ; which is a beneficial 
 circumstance, as the taste of other countries, 
 which I need not name, is so much refined ' 
 all these circumstances taken into the ac- 
 count, and supposing the Brazil mines prove 
 abortive, cannot but abate a suspicion, that 
 has been entertained, concerning this part 
 of the world being glutted with diamonds ; 
 which, it is thought by such persons, will in 
 time sink the price of them. 
 
 Judging those considerations are sufficient 
 to quell such fears, I shall proceed to show 
 it is not the case at present, their price of 
 late being advanced (I mean in Europe only), 
 and the cause of it is this : that most of the 
 capital jewels are returned into the possession 
 of their proper owners, which have some 
 years past been in the hands of usurers, 
 owing to the great expence that some princes 
 
DIAMONDS AND PEARLS. 113 
 
 have been at in the late war; which the 
 peace has not only enabled them to redeem, 
 but likewise qualified them to become far- 
 ther purchasers. And this proves the fitness 
 of pledging jewels rather than selling them 
 below what they ought to fetch, supposing 
 that necessity does not force any thereto ; 
 which is not to be imagined of persons of 
 high rank, or of good estates, as time gives 
 them an opportunity of redeeming any 
 pledges. 
 
 CONCLUSION. 
 
 THIS concludes the important subjects I 
 have been treating of; and the enlarge- 
 ments that have been made to this edition, 
 I flatter myself, will be found not only 
 explanatory of my first publication, but that 
 they will likewise give force to what is 
 therein contained, and which would have 
 been added thereto, had I then seen it to be 
 necessary ; but which I have not been con- 
 vinced of till lately, and now think the omis- 
 
 L 
 
114 A TREATISE ON 
 
 sion of it would be an impediment to my 
 design, which is that of communicating truth 
 and knowledge, beneficial to the public, and 
 to all ingenious traders, and which is calcu- 
 lated to raise their reputations and usefulness, 
 and likewise to promote art in the embel- 
 lishments of diamonds, and recover, if pos- 
 sible, the almost lost manufacture of them to 
 this kingdom, that has in time past been pos- 
 sessed of the chief share thereof, and which 
 has carried the improvement of it to the 
 greatest height of any part of the world, and 
 is now as capable of doing so as ever, if per- 
 mitted ; which I hope to see brought about. 
 
 The loss of this valuable manufacture, 
 and of the trade resulting therefrom, has 
 been wholly owing to a delusive manner of 
 working them abroad, which enables fo- 
 reigners to sell diamonds cheaper by weight 
 than it is possible to afford well-wrought 
 ones for. By this means they are become 
 possessed of almost the whole of this manu- 
 facture and trade. 
 
 And this practice has been much coun- 
 tenanced by some traders in London, who 
 have sold for some years past f or more of 
 
DIAMONDS AND PEARLS. 115 
 
 these foreign-wrought diamonds, to the great 
 discredit of their wearers ; which conduct 
 seems to come but little short of an affront 
 on the quality and gentry of this kingdom, 
 and shows a manifest disregard of the in- 
 terests thereof; which I am sorry to have 
 occasion to take notice of, as well as of 
 some other matters that could not justifi- 
 ably escape my observation, but which I 
 am satisfied will give no offence to any im- 
 partial unprejudiced person ; and the new 
 matter in this edition, I doubt not, will meet 
 with the approbation of the judicious, as it 
 must give an additional enforcement to what 
 is contained in the first, and serve to ren- 
 der these important articles of wealth of 
 more established worth than in times past, 
 since their value appears to be determin- 
 able by rules founded on reason and truth, 
 which has hitherto been subject to the ca- 
 pricious estimation of unguided judgment. 
 And I am the more encouraged to hope for 
 the countenance of such persons, as my first 
 has received that honour, as well among 
 people of rank and condition, as among 
 traders in jewels ; and I have the satisfac- 
 
116 A TREATISE ON DIAMONDS, ETC. 
 
 tion of knowing it daily gains ground, and 
 am particularly pleased in finding a con- 
 siderable increase of business within twelve 
 months past, in the best manner of work- 
 ing diamonds. 
 
 And now being no ways conscious of hav- 
 ing taken any unwarrantable freedoms in 
 any part of this treatise, but pursued truth, 
 justice, and the fitness of things to the best 
 of my knowledge, I shall not trouble my 
 readers with any farther vindication of my 
 conduct. But in respect to any imperfec- 
 tion of style that may appear in this treatise, 
 I hope the candid part of the world will 
 overlook it, as I make no pretension to any 
 accomplishment in that way ; and all that 1 
 have aimed at has been to convey my 
 thoughts in as clear a manner as my abi- 
 lities would enable me to do : and this, I 
 question not, will be accepted as a sufficient 
 apology for any inaccuracy of expression in 
 the book. 
 
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